PERLDIAG(1)

NAME
perldiag - various Perl diagnostics

DESCRIPTION
These messages are classified as follows (listed in increasing order of desperation):

    (W) A warning (optional).
    (D) A deprecation (optional).
    (S) A severe warning (default).
    (F) A fatal error (trappable).
    (P) An internal error you should never see (trappable).
    (X) A very fatal error (nontrappable).
    (A) An alien error message (not generated by Perl).
The majority of messages from the first three classifications above (W, D & S) can be controlled using the "warnings" pragma.

If a message can be controlled by the "warnings" pragma, its warning category is included with the classification letter in the description below.

Optional warnings are enabled by using the "warnings" pragma or the -w and -W switches. Warnings may be captured by setting "$SIG{__WARN__}" to a reference to a routine that will be called on each warning instead of printing it. See the perlvar manpage.

Default warnings are always enabled unless they are explicitly disabled with the "warnings" pragma or the -X switch.

Trappable errors may be trapped using the eval operator. See the eval entry in the perlfunc manpage. In almost all cases, warnings may be selectively disabled or promoted to fatal errors using the "warnings" pragma. See the warnings manpage.

The messages are in alphabetical order, without regard to upper or lower-case. Some of these messages are generic. Spots that vary are denoted with a %s or other printf-style escape. These escapes are ignored by the alphabetical order, as are all characters other than letters. To look up your message, just ignore anything that is not a letter. (W closed) You tried to do an accept on a closed socket. Did you forget to check the return value of your socket() call? See the accept entry in the perlfunc manpage. (X) You can't allocate more than 64K on an MS-DOS machine. (F) The '!' is allowed in pack() and unpack() only after certain types. See the pack entry in the perlfunc manpage. (W ambiguous) A subroutine you have declared has the same name as a Perl keyword, and you have used the name without qualification for calling one or the other. Perl decided to call the builtin because the subroutine is not imported.

To force interpretation as a subroutine call, either put an ampersand before the subroutine name, or qualify the name with its package. Alternatively, you can import the subroutine (or pretend that it's imported with the "use subs" pragma).

To silently interpret it as the Perl operator, use the "CORE::" prefix on the operator (e.g. "CORE::log($x)") or by declaring the subroutine to be an object method (see the Subroutine Attributes entry in the perlsub manpage or the attributes manpage). (W ambiguous)(S) You said something that may not be interpreted the way you thought. Normally it's pretty easy to disambiguate it by supplying a missing quote, operator, parenthesis pair or declaration. (F) An error peculiar to VMS. Perl does its own command line redirection, and found that STDIN was a pipe, and that you also tried to redirect STDIN using '<'. Only one STDIN stream to a customer, please. (F) An error peculiar to VMS. Perl does its own command line redirection, and thinks you tried to redirect stdout both to a file and into a pipe to another command. You need to choose one or the other, though nothing's stopping you from piping into a program or Perl script which 'splits' output into two streams, such as

    open(OUT,">$ARGV[0]") or die "Can't write to $ARGV[0]: $!";
    while (<STDIN>) {
        print;
        print OUT;
    }
    close OUT;
(W misc) The pattern match (//), substitution (s///), and transliteration (tr///) operators work on scalar values. If you apply one of them to an array or a hash, it will convert the array or hash to a scalar value -- the length of an array, or the population info of a hash -- and then work on that scalar value. This is probably not what you meant to do. See the grep entry in the perlfunc manpage and the map entry in the perlfunc manpage for alternatives. (F) The setuid emulator requires that the arguments Perl was invoked with match the arguments specified on the #! line. Since some systems impose a one-argument limit on the #! line, try combining switches; for example, turn "-w -U" into "-wU". (F) msgsnd() requires a string at least as long as sizeof(long). (F) The argument to exists() must be a hash or array element, such as:

    $foo{$bar}
    $ref->{"susie"}[12]
(F) The argument to delete() must be either a hash or array element, such as:

    $foo{$bar}
    $ref->{"susie"}[12]
or a hash or array slice, such as:

    @foo[$bar, $baz, $xyzzy]
    @{$ref->[12]}{"susie", "queue"}
(F) The argument to exists() for "exists &sub" must be a subroutine name, and not a subroutine call. "exists &sub()" will generate this error. (W numeric) The indicated string was fed as an argument to an operator that expected a numeric value instead. If you're fortunate the message will identify which operator was so unfortunate. (D deprecated) Really old Perl let you omit the @ on array names in some spots. This is now heavily deprecated. (P) The malloc package that comes with Perl had an internal failure. (P) A general assertion failed. The file in question must be examined. (F) If you assign to a conditional operator, the 2nd and 3rd arguments must either both be scalars or both be lists. Otherwise Perl won't know which context to supply to the right side. (F) When vec is called in an lvalue context, the second argument must be greater than or equal to zero. (P internal) All SV objects are supposed to be allocated from arenas that will be garbage collected on exit. An SV was discovered to be outside any of those arenas. (P internal) Perl maintains a reference counted internal table of strings to optimize the storage and access of hash keys and other strings. This indicates someone tried to decrement the reference count of a string that can no longer be found in the table. (W debugging) Mortalized values are supposed to be freed by the free_tmps() routine. This indicates that something else is freeing the SV before the free_tmps() routine gets a chance, which means that the free_tmps() routine will be freeing an unreferenced scalar when it does try to free it. (P internal) The reference counts got screwed up on symbol aliases. (W internal) Perl went to decrement the reference count of a scalar to see if it would go to 0, and discovered that it had already gone to 0 earlier, and should have been freed, and in fact, probably was freed. This could indicate that SvREFCNT_dec() was called too many times, or that SvREFCNT_inc() was called too few times, or that the SV was mortalized when it shouldn't have been, or that memory has been corrupted. (F) You tried to join a thread from within itself, which is an impossible task. You may be joining the wrong thread, or you may need to move the join() to some other thread. (W pack) You tried to pass a temporary value (like the result of a function, or a computed expression) to the "p" pack() template. This means the result contains a pointer to a location that could become invalid anytime, even before the end of the current statement. Use literals or global values as arguments to the "p" pack() template to avoid this warning. (W substr) You supplied a reference as the first argument to substr() used as an lvalue, which is pretty strange. Perhaps you forgot to dereference it first. See the substr entry in the perlfunc manpage. (F) You passed a buffer of the wrong size to one of msgctl(), semctl() or shmctl(). In C parlance, the correct sizes are, respectively, sizeof(struct msqid_ds *), sizeof(struct semid_ds *), and sizeof(struct shmid_ds *). (F) You've used the /e switch to evaluate the replacement for a substitution, but perl found a syntax error in the code to evaluate, most likely an unexpected right brace '}'. (F) A symbol was passed to something wanting a filehandle, but the symbol has no filehandle associated with it. Perhaps you didn't do an open(), or did it in another package. (S malloc) An internal routine called free() on something that had never been malloc()ed in the first place. Mandatory, but can be disabled by setting environment variable "PERL_BADFREE" to 0.

This message can be seen quite often with DB_File on systems with "hard" dynamic linking, like "AIX" and "OS/2". It is a bug of "Berkeley DB" which is left unnoticed if "DB" uses forgiving system malloc(). (P) One of the internal hash routines was passed a null HV pointer. (F) The index looked up in the hash found as the 0'th element of a pseudo-hash is not legal. Index values must be at 1 or greater. See the perlref manpage. (A) You've accidentally run your script through csh instead of Perl. Check the #! line, or manually feed your script into Perl yourself. (F) You started to name a symbol by using a package prefix, and then didn't finish the symbol. In particular, you can't interpolate outside of quotes, so

    $var = 'myvar';
    $sym = mypack::$var;
is not the same as

    $var = 'myvar';
    $sym = "mypack::$var";
(S malloc) An internal routine called realloc() on something that had never been malloc()ed in the first place. Mandatory, but can be disabled by setting environment variable "PERL_BADFREE" to 1. (P) An internal request asked to add an array entry to something that wasn't a symbol table entry. (P) An internal request asked to add a filehandle entry to something that wasn't a symbol table entry. (P) An internal request asked to add a hash entry to something that wasn't a symbol table entry. (W bareword) The compiler found a bareword where it expected a conditional, which often indicates that an || or && was parsed as part of the last argument of the previous construct, for example:

    open FOO || die;
It may also indicate a misspelled constant that has been interpreted as a bareword:

    use constant TYPO => 1;
    if (TYOP) { print "foo" }
The "strict" pragma is useful in avoiding such errors. (F) With "strict subs" in use, a bareword is only allowed as a subroutine identifier, in curly brackets or to the left of the "=>" symbol. Perhaps you need to predeclare a subroutine? (W bareword) You used a qualified bareword of the form "Foo::", but the compiler saw no other uses of that namespace before that point. Perhaps you need to predeclare a package? (F) An untrapped exception was raised while executing a BEGIN subroutine. Compilation stops immediately and the interpreter is exited. (F) Perl found a "BEGIN {}" subroutine (or a "use" directive, which implies a "BEGIN {}") after one or more compilation errors had already occurred. Since the intended environment for the "BEGIN {}" could not be guaranteed (due to the errors), and since subsequent code likely depends on its correct operation, Perl just gave up. (W syntax) Outside of patterns, backreferences live on as variables. The use of backslashes is grandfathered on the right-hand side of a substitution, but stylistically it's better to use the variable form because other Perl programmers will expect it, and it works better if there are more than 9 backreferences. (W portable) The binary number you specified is larger than 2**32-1 (4294967295) and therefore non-portable between systems. See the perlport manpage for more on portability concerns. (W closed) You tried to do a bind on a closed socket. Did you forget to check the return value of your socket() call? See the bind entry in the perlfunc manpage. (W portable) Using bit vector sizes larger than 32 is non-portable. (P) Perl detected an attempt to copy an internal value that is not copyable. (F) The script would have to be opened by the C preprocessor by name, which provides a race condition that breaks security. (W internal) A warning peculiar to VMS. While Perl was preparing to iterate over %ENV, it encountered a logical name or symbol definition which was too long, so it was truncated to the string shown. (F) A subroutine invoked from an external package via call_sv() exited by calling exit. (W prototype) You've called a function that has a prototype before the parser saw a definition or declaration for it, and Perl could not check that the call conforms to the prototype. You need to either add an early prototype declaration for the subroutine in question, or move the subroutine definition ahead of the call to get proper prototype checking. Alternatively, if you are certain that you're calling the function correctly, you may put an ampersand before the name to avoid the warning. See the perlsub manpage. (F) You had an unpack template indicating a counted-length string, but you have also specified an explicit size for the string. See the pack entry in the perlfunc manpage. (F) Only hard references may be blessed. This is how Perl "enforces" encapsulation of objects. See the perlobj manpage. (F) You called a method correctly, and it correctly indicated a package functioning as a class, but that package doesn't have ANYTHING defined in it, let alone methods. See the perlobj manpage. (F) You used the syntax of a method call, but the slot filled by the object reference or package name contains an undefined value. Something like this will reproduce the error:

    $BADREF = undef;
    process $BADREF 1,2,3;
    $BADREF->process(1,2,3);
(F) A method call must know in what package it's supposed to run. It ordinarily finds this out from the object reference you supply, but you didn't supply an object reference in this case. A reference isn't an object reference until it has been blessed. See the perlobj manpage. (F) You used the syntax of a method call, but the slot filled by the object reference or package name contains an expression that returns a defined value which is neither an object reference nor a package name. Something like this will reproduce the error:

    $BADREF = 42;
    process $BADREF 1,2,3;
    $BADREF->process(1,2,3);
(F) You called "perl -x/foo/bar", but "/foo/bar" is not a directory that you can chdir to, possibly because it doesn't exist. (P) For some reason you can't check the filesystem of the script for nosuid. (F) You used an array where a hash was expected, but the array has no information on how to map from keys to array indices. You can do that only with arrays that have a hash reference at index 0. (F) Certain types of SVs, in particular real symbol table entries (typeglobs), can't be forced to stop being what they are. So you can't say things like:

    *foo += 1;
You CAN say

    $foo = *foo;
    $foo += 1;
but then $foo no longer contains a glob. (F) Certain types of SVs, in particular real symbol table entries (typeglobs), can't be forced to stop being what they are. (F) Certain types of SVs, in particular real symbol table entries (typeglobs), can't be forced to stop being what they are. (P) An error peculiar to VMS. The process is suffering from exhausted quotas or other plumbing problems. (S) Currently, only scalar variables can declared with a specific class qualifier in a "my" or "our" declaration. The semantics may be extended for other types of variables in future. (F) Only scalar, array, and hash variables may be declared as "my" or "our" variables. They must have ordinary identifiers as names. (S inplace) You tried to use the -i switch on a special file, such as a file in /dev, or a FIFO. The file was ignored. (S inplace) The creation of the new file failed for the indicated reason. (F) You're on a system such as MS-DOS that gets confused if you try reading from a deleted (but still opened) file. You have to say "-i.bak", or some such. (S inplace) Your filesystem does not support filenames longer than 14 characters and Perl was unable to create a unique filename during inplace editing with the -i switch. The file was ignored. (F) Minima must be less than or equal to maxima. If you really want your regexp to match something 0 times, just put {0}. The << HERE shows in the regular expression about where the problem was discovered. See the perlre manpage. (P) The setegid() call failed for some reason in the setuid emulator of suidperl. (P) The setuid emulator of suidperl failed for some reason. (F) This typically means that ordinary perl tried to exec suidperl to do setuid emulation, but couldn't exec it. It looks for a name of the form sperl5.000 in the same directory that the perl executable resides under the name perl5.000, typically /usr/local/bin on Unix machines. If the file is there, check the execute permissions. If it isn't, ask your sysadmin why he and/or she removed it. (F) This machine doesn't have either waitpid() or wait4(), so only waitpid() without flags is emulated. (F) The #! line specifies a switch that doesn't make sense at this point. For example, it'd be kind of silly to put a -x on the #! line. (W exec) An system(), exec(), or piped open call could not execute the named program for the indicated reason. Typical reasons include: the permissions were wrong on the file, the file wasn't found in "$ENV{PATH}", the executable in question was compiled for another architecture, or the #! line in a script points to an interpreter that can't be run for similar reasons. (Or maybe your system doesn't support #! at all.) (F) Perl was trying to execute the indicated program for you because that's what the #! line said. If that's not what you wanted, you may need to mention "perl" on the #! line somewhere. (F) You used the -S switch, but the copies of the script to execute found in the PATH did not have correct permissions. (F) A string of a form "CORE::word" was given to prototype(), but there is no builtin with the name "word". (F) You said to goto a label that isn't mentioned anywhere that it's possible for us to go to. See the goto entry in the perlfunc manpage. (F) You used the -S switch, but the script to execute could not be found in the PATH. (F) You used the -S switch, but the script to execute could not be found in the PATH, or at least not with the correct permissions. The script exists in the current directory, but PATH prohibits running it. (F) Perl strings can stretch over multiple lines. This message means that the closing delimiter was omitted. Because bracketed quotes count nesting levels, the following is missing its final parenthesis:

    print q(The character '(' starts a side comment.);
If you're getting this error from a here-document, you may have included unseen whitespace before or after your closing tag. A good programmer's editor will have a way to help you find these characters. (F) You may have tried to use "\p" which means a Unicode property for example \p{Lu} is all uppercase letters. Escape the "\p", either "\\p" (just the "\p") or by "\Q\p" (the rest of the string, until possible "\E"). (F) A fatal error occurred while trying to fork while opening a pipeline. (S) A warning peculiar to VMS. This arises because of the difference between access checks under VMS and under the Unix model Perl assumes. Under VMS, access checks are done by filename, rather than by bits in the stat buffer, so that ACLs and other protections can be taken into account. Unfortunately, Perl assumes that the stat buffer contains all the necessary information, and passes it, instead of the filespec, to the access checking routine. It will try to retrieve the filespec using the device name and FID present in the stat buffer, but this works only if you haven't made a subsequent call to the CRTL stat() routine, because the device name is overwritten with each call. If this warning appears, the name lookup failed, and the access checking routine gave up and returned FALSE, just to be conservative. (Note: The access checking routine knows about the Perl "stat" operator and file tests, so you shouldn't ever see this warning in response to a Perl command; it arises only if some internal code takes stat buffers lightly.) (P) An error peculiar to VMS. After creating a mailbox to act as a pipe, Perl can't retrieve its name for later use. (P) An error peculiar to VMS. Perl asked $GETSYI how big you want your mailbox buffers to be, and didn't get an answer. (F) A "goto" statement was executed to jump into the middle of a foreach loop. You can't get there from here. See the goto entry in the perlfunc manpage. (F) A "goto" statement was executed to jump out of what might look like a block, except that it isn't a proper block. This usually occurs if you tried to jump out of a sort() block or subroutine, which is a no-no. See the goto entry in the perlfunc manpage. (F) The "goto subroutine" call can't be used to jump out of an eval "string". (You can use it to jump out of an eval {BLOCK}, but you probably don't want to.) (F) The deeply magical "goto subroutine" call can only replace one subroutine call for another. It can't manufacture one out of whole cloth. In general you should be calling it out of only an AUTOLOAD routine anyway. See the goto entry in the perlfunc manpage. (W signal) Perl has detected that it is being run with the SIGCHLD signal (sometimes known as SIGCLD) disabled. Since disabling this signal will interfere with proper determination of exit status of child processes, Perl has reset the signal to its default value. This situation typically indicates that the parent program under which Perl may be running (e.g. cron) is being very careless. (F) A "last" statement was executed to break out of the current block, except that there's this itty bitty problem called there isn't a current block. Note that an "if" or "else" block doesn't count as a "loopish" block, as doesn't a block given to sort(), map() or grep(). You can usually double the curlies to get the same effect though, because the inner curlies will be considered a block that loops once. See the last entry in the perlfunc manpage. (F) You used local on a variable name that was previously declared as a lexical variable using "my". This is not allowed. If you want to localize a package variable of the same name, qualify it with the package name. (F) You said something like "local $ar->{'key'}", where $ar is a reference to a pseudo-hash. That hasn't been implemented yet, but you can get a similar effect by localizing the corresponding array element directly -- "local $ar->[$ar->[0]{'key'}]". (F) You said something like "local $$ref", which Perl can't currently handle, because when it goes to restore the old value of whatever $ref pointed to after the scope of the local() is finished, it can't be sure that $ref will still be a reference. (F) You said to "do" (or "require", or "use") a file that couldn't be found. Perl looks for the file in all the locations mentioned in @INC, unless the file name included the full path to the file. Perhaps you need to set the PERL5LIB or PERL5OPT environment variable to say where the extra library is, or maybe the script needs to add the library name to @INC. Or maybe you just misspelled the name of the file. See the require entry in the perlfunc manpage and the lib manpage. (F) A function (or method) was called in a package which allows autoload, but there is no function to autoload. Most probable causes are a misprint in a function/method name or a failure to "AutoSplit" the file, say, by doing "make install". (F) You called a method correctly, and it correctly indicated a package functioning as a class, but that package doesn't define that particular method, nor does any of its base classes. See the perlobj manpage. (F) This is an educated guess made in conjunction with the message "Can't locate object method \"%s\" via package \"%s\"". It often means that a method requires a package that has not been loaded. (W syntax) The @ISA array contained the name of another package that doesn't seem to exist. (F) List assignment to %ENV is not supported on some systems, notably VMS. (F) You aren't allowed to assign to the item indicated, or otherwise try to change it, such as with an auto-increment. (P) The internal routine that does assignment to a substr() was handed a NULL. (F) Subroutines meant to be used in lvalue context should be declared as such, see the Lvalue subroutines entry in the perlsub manpage. (F) The target of a msgrcv must be modifiable to be used as a receive buffer. (F) A "next" statement was executed to reiterate the current block, but there isn't a current block. Note that an "if" or "else" block doesn't count as a "loopish" block, as doesn't a block given to sort(), map() or grep(). You can usually double the curlies to get the same effect though, because the inner curlies will be considered a block that loops once. See the next entry in the perlfunc manpage. (S inplace) The implicit opening of a file through use of the "<>" filehandle, either implicitly under the "-n" or "-p" command-line switches, or explicitly, failed for the indicated reason. Usually this is because you don't have read permission for a file which you named on the command line. (W pipe) You tried to say "open(CMD, "|cmd|")", which is not supported. You can try any of several modules in the Perl library to do this, such as IPC::Open2. Alternately, direct the pipe's output to a file using ">", and then read it in under a different file handle. (F) An error peculiar to VMS. Perl does its own command line redirection, and couldn't open the file specified after '2>' or '2>>' on the command line for writing. (F) An error peculiar to VMS. Perl does its own command line redirection, and couldn't open the file specified after '<' on the command line for reading. (F) An error peculiar to VMS. Perl does its own command line redirection, and couldn't open the file specified after '>' or '>>' on the command line for writing. (P) An error peculiar to VMS. Perl does its own command line redirection, and couldn't open the pipe into which to send data destined for stdout. (F) The script you specified can't be opened for the indicated reason. (S) A warning peculiar to VMS. Perl tried to read an element of %ENV from the CRTL's internal environment array and discovered the array was missing. You need to figure out where your CRTL misplaced its environ or define PERL_ENV_TABLES (see the perlvms manpage) so that environ is not searched. (F) Perl optimizes the internal handling of sort subroutines and keeps pointers into them. You tried to redefine one such sort subroutine when it was currently active, which is not allowed. If you really want to do this, you should write "sort { &func } @x" instead of "sort func @x". (F) A "redo" statement was executed to restart the current block, but there isn't a current block. Note that an "if" or "else" block doesn't count as a "loopish" block, as doesn't a block given to sort(), map() or grep(). You can usually double the curlies to get the same effect though, because the inner curlies will be considered a block that loops once. See the redo entry in the perlfunc manpage. (S inplace) You requested an inplace edit without creating a backup file. Perl was unable to remove the original file to replace it with the modified file. The file was left unmodified. (S inplace) The rename done by the -i switch failed for some reason, probably because you don't have write permission to the directory. (P) An error peculiar to VMS. Perl thought stdin was a pipe, and tried to reopen it to accept binary data. Alas, it failed. (F|P) Error resolving overloading specified by a method name (as opposed to a subroutine reference): no such method callable via the package. If method name is "???", this is an internal error. (P) The setreuid() call failed for some reason in the setuid emulator of suidperl. (F) Perl detected an attempt to return illegal lvalues (such as temporary or readonly values) from a subroutine used as an lvalue. This is not allowed. (F) You tried to return a complete array or hash from an lvalue subroutine, but you called the subroutine in a way that made Perl think you meant to return only one value. You probably meant to write parentheses around the call to the subroutine, which tell Perl that the call should be in list context. (F) The return statement was executed in mainline code, that is, where there was no subroutine call to return out of. See the perlsub manpage. (P) For some reason you can't fstat() the script even though you have it open already. Bizarre. (P) The setreuid() call failed for some reason in the setuid emulator of suidperl. (F) For ordinary real numbers, you can't take the logarithm of a negative number or zero. There's a Math::Complex package that comes standard with Perl, though, if you really want to do that for the negative numbers. (F) For ordinary real numbers, you can't take the square root of a negative number. There's a Math::Complex package that comes standard with Perl, though, if you really want to do that. (F) You can't undefine a routine that's currently running. You can, however, redefine it while it's running, and you can even undef the redefined subroutine while the old routine is running. Go figure. (F) You tried to unshift an "unreal" array that can't be unshifted, such as the main Perl stack. (P) The internal sv_upgrade routine adds "members" to an SV, making it into a more specialized kind of SV. The top several SV types are so specialized, however, that they cannot be interconverted. This message indicates that such a conversion was attempted. (P) The undefined SV is the bottom of the totem pole, in the scheme of upgradability. Upgrading to undef indicates an error in the code calling sv_upgrade. (F) A value used as either a hard reference or a symbolic reference must be a defined value. This helps to delurk some insidious errors. (F) Only hard references are allowed by "strict refs". Symbolic references are disallowed. See the perlref manpage. (F) The first time the %! hash is used, perl automatically loads the Errno.pm module. The Errno module is expected to tie the %! hash to provide symbolic names for "$!" errno values. (F) Only a simple scalar variable may be used as a loop variable on a foreach. (F) You tried to declare a magical variable as a lexical variable. This is not allowed, because the magic can be tied to only one location (namely the global variable) and it would be incredibly confusing to have variables in your program that looked like magical variables but weren't. (F) The global variables $a and $b are reserved for sort comparisons. You mentioned $a or $b in the same line as the <=> or cmp operator, and the variable had earlier been declared as a lexical variable. Either qualify the sort variable with the package name, or rename the lexical variable. (F) You've mixed up your reference types. You have to dereference a reference of the type needed. You can use the ref() function to test the type of the reference, if need be. (F) Only hard references are allowed by "strict refs". Symbolic references are disallowed. See the perlref manpage. (F) The compiler tried to interpret a bracketed expression as a subscript. But to the left of the brackets was an expression that didn't look like an array reference, or anything else subscriptable. (W syntax) In an ordinary expression, backslash is a unary operator that creates a reference to its argument. The use of backslash to indicate a backreference to a matched substring is valid only as part of a regular expression pattern. Trying to do this in ordinary Perl code produces a value that prints out looking like SCALAR(0xdecaf). Use the $1 form instead. (F) You attempted to weaken something that was not a reference. Only references can be weakened. (F) You tried to repeat a constant value (often the undefined value) with an assignment operator, which implies modifying the value itself. Perhaps you need to copy the value to a temporary, and repeat that. (W chmod) A novice will sometimes say

    chmod 777, $filename
not realizing that 777 will be interpreted as a decimal number, equivalent to 01411. Octal constants are introduced with a leading 0 in Perl, as in C. (W unopened) You tried to close a filehandle that was never opened. (A) You've accidentally run your script through csh instead of Perl. Check the #! line, or manually feed your script into Perl yourself. (F) Perl could not compile a file specified in a "require" statement. Perl uses this generic message when none of the errors that it encountered were severe enough to halt compilation immediately. (W regexp) The regular expression engine uses recursion in complex situations where back-tracking is required. Recursion depth is limited to 32766, or perhaps less in architectures where the stack cannot grow arbitrarily. ("Simple" and "medium" situations are handled without recursion and are not subject to a limit.) Try shortening the string under examination; looping in Perl code (e.g. with "while") rather than in the regular expression engine; or rewriting the regular expression so that it is simpler or backtracks less. (See the perlfaq2 manpage for information on Mastering Regular Expressions.) (W closed) You tried to do a connect on a closed socket. Did you forget to check the return value of your socket() call? See the connect entry in the perlfunc manpage. (F) The parser found inconsistencies either while attempting to define an overloaded constant, or when trying to find the character name specified in the "\N{...}" escape. Perhaps you forgot to load the corresponding "overload" or "charnames" pragma? See the charnames manpage and the overload manpage. (F) A constant value (perhaps declared using the "use constant" pragma) is being dereferenced, but it amounts to the wrong type of reference. The message indicates the type of reference that was expected. This usually indicates a syntax error in dereferencing the constant value. See the Constant Functions entry in the perlsub manpage and the constant manpage. (S|W redefine) You redefined a subroutine which had previously been eligible for inlining. See the Constant Functions entry in the perlsub manpage for commentary and workarounds. (W misc) You undefined a subroutine which had previously been eligible for inlining. See the Constant Functions entry in the perlsub manpage for commentary and workarounds. (F) The method which overloads "=" is buggy. See the Copy Constructor entry in the overload manpage. (F) The CORE:: namespace is reserved for Perl keywords. (P) The regular expression engine got confused by what the regular expression compiler gave it. (P) The regular expression engine got passed a regexp program without a valid magic number. (P) The malloc package that comes with Perl had an internal failure. (F) An error occurred during the implicit output invoked by the "-p" command-line switch. (This output goes to STDOUT unless you've redirected it with select().) (F) Perl can't peek at the stdio buffer of filehandles when it doesn't know about your kind of stdio. You'll have to use a filename instead. (W recursion) This subroutine has called itself (directly or indirectly) 100 times more than it has returned. This probably indicates an infinite recursion, unless you're writing strange benchmark programs, in which case it indicates something else. (D deprecated) defined() is not usually useful on arrays because it checks for an undefined scalar value. If you want to see if the array is empty, just use "if (@array) { # not empty }" for example. (D deprecated) defined() is not usually useful on hashes because it checks for an undefined scalar value. If you want to see if the hash is empty, just use "if (%hash) { # not empty }" for example. (F) In a here document construct like "<<FOO", the label "FOO" is too long for Perl to handle. You have to be seriously twisted to write code that triggers this error. See Server error. (F) A required (or used) file must return a true value to indicate that it compiled correctly and ran its initialization code correctly. It's traditional to end such a file with a "1;", though any true value would do. See the require entry in the perlfunc manpage. (W) You probably referred to an imported subroutine &FOO as $FOO or some such. (W misc) Remember that "our" does not localize the declared global variable. You have declared it again in the same lexical scope, which seems superfluous. (W) You probably said %hash{$key} when you meant $hash{$key} or @hash{@keys}. On the other hand, maybe you just meant %hash and got carried away. (F) You passed die() an empty string (the equivalent of "die """) or you called it with no args and both "$@" and "$_" were empty. See Server error. (P) The internal handling of magical variables has been cursed. (P) This should have been caught by safemalloc() instead. (S) This is an educated guess made in conjunction with the message "%s found where operator expected". It often means a subroutine or module name is being referenced that hasn't been declared yet. This may be because of ordering problems in your file, or because of a missing "sub", "package", "require", or "use" statement. If you're referencing something that isn't defined yet, you don't actually have to define the subroutine or package before the current location. You can use an empty "sub foo;" or "package FOO;" to enter a "forward" declaration. (S malloc) An internal routine called free() on something that had already been freed. (S) There is no keyword "elseif" in Perl because Larry thinks it's ugly. Your code will be interpreted as an attempt to call a method named "elseif" for the class returned by the following block. This is unlikely to be what you want. (F) While under the "use filetest" pragma, switching the real and effective uids or gids failed. (F) An error peculiar to VMS. Because Perl may have to deal with file specifications in either VMS or Unix syntax, it converts them to a single form when it must operate on them directly. Either you've passed an invalid file specification to Perl, or you've found a case the conversion routines don't handle. Drat. (F) Perl detected tainted data when trying to compile a regular expression that contains the "(?{ ... })" zero-width assertion, which is unsafe. See the section on "(?{ code })" in the perlre manpage, and the perlsec manpage. (F) Perl tried to compile a regular expression containing the "(?{ ... })" zero-width assertion at run time, as it would when the pattern contains interpolated values. Since that is a security risk, it is not allowed. If you insist, you may still do this by explicitly building the pattern from an interpolated string at run time and using that in an eval(). See the section on "(?{ code })" in the perlre manpage. (F) A regular expression contained the "(?{ ... })" zero-width assertion, but that construct is only allowed when the "use re 'eval'" pragma is in effect. See the section on "(?{ code })" in the perlre manpage. (F) The contents of a <> operator may not exceed the maximum size of a Perl identifier. If you're just trying to glob a long list of filenames, try using the glob() operator, or put the filenames into a variable and glob that. (F) The final summary message when a Perl compilation fails. (W exiting) You are exiting an eval by unconventional means, such as a goto, or a loop control statement. (W exiting) You are exiting an eval by unconventional means, such as a goto, or a loop control statement. (W exiting) You are exiting a rather special block construct (like a sort block or subroutine) by unconventional means, such as a goto, or a loop control statement. See the sort entry in the perlfunc manpage. (W exiting) You are exiting a subroutine by unconventional means, such as a goto, or a loop control statement. (W exiting) You are exiting a substitution by unconventional means, such as a return, a goto, or a loop control statement. (W misc) You are blessing a reference to a zero length string. This has the effect of blessing the reference into the package main. This is usually not what you want. Consider providing a default target package, e.g. bless($ref, $p || 'MyPackage'); (A) You've accidentally run your script through csh instead of Perl. Check the #! line, or manually feed your script into Perl yourself. (F) An untrapped exception was raised while executing a CHECK, INIT, or END subroutine. Processing of the remainder of the queue of such routines has been prematurely ended. (W regexp) A character class range must start and end at a literal character, not another character class like "\d" or "[:alpha:]". The "-" in your false range is interpreted as a literal "-". Consider quoting the "-", "\-". See the perlre manpage. (P) An error peculiar to VMS. Something untoward happened in a VMS system service or RTL routine; Perl's exit status should provide more details. The filename in "at %s" and the line number in "line %d" tell you which section of the Perl source code is distressed. (F) Your machine apparently doesn't implement fcntl(). What is this, a PDP-11 or something? (W io) You tried to write on a read-only filehandle. If you intended it to be a read-write filehandle, you needed to open it with "+<" or "+>" or "+>>" instead of with "<" or nothing. If you intended only to write the file, use ">" or ">>". See the open entry in the perlfunc manpage. (W io) You tried to read from a filehandle opened only for writing. If you intended it to be a read/write filehandle, you needed to open it with "+<" or "+>" or "+>>" instead of with "<" or nothing. If you intended only to read from the file, use "<". See the open entry in the perlfunc manpage. (F) You must now decide whether the final $ in a string was meant to be a literal dollar sign, or was meant to introduce a variable name that happens to be missing. So you have to put either the backslash or the name. (F) You must now decide whether the final @ in a string was meant to be a literal "at" sign, or was meant to introduce a variable name that happens to be missing. So you have to put either the backslash or the name. (W closed) The filehandle you're attempting to flock() got itself closed some time before now. Check your logic flow. flock() operates on filehandles. Are you attempting to call flock() on a dirhandle by the same name? (F) You started a regular expression with a quantifier. Backslash it if you meant it literally. The << HERE shows in the regular expression about where the problem was discovered. See the perlre manpage. (F) A format must be terminated by a line with a solitary dot. Perl got to the end of your file without finding such a line. (W redefine) You redefined a format. To suppress this warning, say

    {
        no warnings;
        eval "format NAME =...";
    }
(W syntax) You said

    if ($foo = 123)
when you meant

    if ($foo == 123)
(or something like that). (S) The Perl lexer knows whether to expect a term or an operator. If it sees what it knows to be a term when it was expecting to see an operator, it gives you this warning. Usually it indicates that an operator or delimiter was omitted, such as a semicolon. (S) A warning from the GDBM_File extension that a store failed. (F) Your C library apparently doesn't implement gethostent(), probably because if it did, it'd feel morally obligated to return every hostname on the Internet. (W closed) You tried to get a socket or peer socket name on a closed socket. Did you forget to check the return value of your socket() call? (S) A warning peculiar to VMS. The call to "sys$getuai" underlying the "getpwnam" operator returned an invalid UIC. (W closed) You tried to get a socket option on a closed socket. Did you forget to check the return value of your socket() call? See the getsockopt entry in the perlfunc manpage. (F) You've said "use strict vars", which indicates that all variables must either be lexically scoped (using "my"), declared beforehand using "our", or explicitly qualified to say which package the global variable is in (using "::"). (W glob) Something went wrong with the external program(s) used for "glob" and "<*.c>". Usually, this means that you supplied a "glob" pattern that caused the external program to fail and exit with a nonzero status. If the message indicates that the abnormal exit resulted in a coredump, this may also mean that your csh (C shell) is broken. If so, you should change all of the csh-related variables in config.sh: If you have tcsh, make the variables refer to it as if it were csh (e.g. "full_csh='/usr/bin/tcsh'"); otherwise, make them all empty (except that "d_csh" should be "'undef'") so that Perl will think csh is missing. In either case, after editing config.sh, run "./Configure -S" and rebuild Perl. (F) The lexer saw a left angle bracket in a place where it was expecting a term, so it's looking for the corresponding right angle bracket, and not finding it. Chances are you left some needed parentheses out earlier in the line, and you really meant a "less than". (P) An error peculiar to OS/2. Most probably you're using an obsolete version of Perl, and this should not happen anyway. (F) Unlike with "next" or "last", you're not allowed to goto an unspecified destination. See the goto entry in the perlfunc manpage. (F) The final summary message when a "perl -c" fails. (S internal) A routine asked for a symbol from a symbol table that ought to have existed already, but for some reason it didn't, and had to be created on an emergency basis to prevent a core dump. (D deprecated) Really old Perl let you omit the % on hash names in some spots. This is now heavily deprecated. (F) The parser has given up trying to parse the program after 10 errors. Further error messages would likely be uninformative. (W portable) The hexadecimal number you specified is larger than 2**32-1 (4294967295) and therefore non-portable between systems. See the perlport manpage for more on portability concerns. (F) Perl limits identifiers (names for variables, functions, etc.) to about 250 characters for simple names, and somewhat more for compound names (like "$A::B"). You've exceeded Perl's limits. Future versions of Perl are likely to eliminate these arbitrary limitations. (F) You used a digit other than 0 or 1 in a binary number. (W digit) You may have tried to use a digit other than 0 or 1 in a binary number. Interpretation of the binary number stopped before the offending digit. (F) Perl normally treats carriage returns in the program text as it would any other whitespace, which means you should never see this error when Perl was built using standard options. For some reason, your version of Perl appears to have been built without this support. Talk to your Perl administrator. (F) You tried to divide a number by 0. Either something was wrong in your logic, or you need to put a conditional in to guard against meaningless input. (W digit) You may have tried to use a character other than 0 - 9 or A - F, a - f in a hexadecimal number. Interpretation of the hexadecimal number stopped before the illegal character. (F) You tried to divide a number by 0 to get the remainder. Most numbers don't take to this kindly. (F) The number of bits in vec() (the third argument) must be a power of two from 1 to 32 (or 64, if your platform supports that). (F) You used an 8 or 9 in a octal number. (W digit) You may have tried to use an 8 or 9 in a octal number. Interpretation of the octal number stopped before the 8 or 9. (X) The PERL5OPT environment variable may only be used to set the following switches: -[DIMUdmw]. (W internal) A warning peculiar to VMS. Perl tried to read the CRTL's internal environ array, and encountered an element without the "=" delimiter used to separate keys from values. The element is ignored. (W internal) A warning peculiar to VMS. Perl tried to read a logical name or CLI symbol definition when preparing to iterate over %ENV, and didn't see the expected delimiter between key and value, so the line was ignored. (W misc) This prefix usually indicates that a DESTROY() method raised the indicated exception. Since destructors are usually called by the system at arbitrary points during execution, and often a vast number of times, the warning is issued only once for any number of failures that would otherwise result in the same message being repeated.

Failure of user callbacks dispatched using the "G_KEEPERR" flag could also result in this warning. See the G_KEEPERR entry in the perlcall manpage. (F) You tried to do something that the tainting mechanism didn't like. The tainting mechanism is turned on when you're running setuid or setgid, or when you specify -T to turn it on explicitly. The tainting mechanism labels all data that's derived directly or indirectly from the user, who is considered to be unworthy of your trust. If any such data is used in a "dangerous" operation, you get this error. See the perlsec manpage for more information. (F) You can't use system(), exec(), or a piped open in a setuid or setgid script if "$ENV{PATH}" contains a directory that is writable by the world. See the perlsec manpage. (F) You can't use system(), exec(), or a piped open in a setuid or setgid script if any of "$ENV{PATH}", "$ENV{IFS}", "$ENV{CDPATH}", "$ENV{ENV}" or "$ENV{BASH_ENV}" are derived from data supplied (or potentially supplied) by the user. The script must set the path to a known value, using trustworthy data. See the perlsec manpage. (W overflow) The hexadecimal, octal or binary number you have specified either as a literal or as an argument to hex() or oct() is too big for your architecture, and has been converted to a floating point number. On a 32-bit architecture the largest hexadecimal, octal or binary number representable without overflow is 0xFFFFFFFF, 037777777777, or 0b11111111111111111111111111111111 respectively. Note that Perl transparently promotes all numbers to a floating point representation internally--subject to loss of precision errors in subsequent operations. (P) Something went badly wrong in the regular expression parser. The << HERE shows in the regular expression about where the problem was discovered. (S) A warning peculiar to VMS. Perl keeps track of the number of times you've called "fork" and "exec", to determine whether the current call to "exec" should affect the current script or a subprocess (see the exec LIST entry in the perlvms manpage). Somehow, this count has become scrambled, so Perl is making a guess and treating this "exec" as a request to terminate the Perl script and execute the specified command. (P) Something went badly awry in the regular expression parser. The <<<HERE shows in the regular expression about where the problem was discovered. (W syntax) You've run afoul of the rule that says that any list operator followed by parentheses turns into a function, with all the list operators arguments found inside the parentheses. See the Terms and List Operators (Leftward) entry in the perlop manpage. The indicated attribute for a subroutine or variable was not recognized by Perl or by a user-supplied handler. See the attributes manpage. The indicated attributes for a subroutine or variable were not recognized by Perl or by a user-supplied handler. See the attributes manpage. (W printf) Perl does not understand the given format conversion. See the sprintf entry in the perlfunc manpage. (F) The range specified in a character class had a minimum character greater than the maximum character. See the perlre manpage. (F) Something other than a colon or whitespace was seen between the elements of an attribute list. If the previous attribute had a parenthesised parameter list, perhaps that list was terminated too soon. See the attributes manpage. (F) The given character is not a valid pack type. See the pack entry in the perlfunc manpage. (W pack) The given character is not a valid pack type but used to be silently ignored. (F) The given character is not a valid unpack type. See the unpack entry in the perlfunc manpage. (W unpack) The given character is not a valid unpack type but used to be silently ignored. (F) Your machine apparently doesn't implement ioctl(), which is pretty strange for a machine that supports C. (W) The second (fourth, sixth, ...) argument of overload::constant needs to be a code reference. Either an anonymous subroutine, or a reference to a subroutine. (W) You tried to overload a constant type the overload package is unaware of. (P) The regular expression parser is confused. (F) You named a loop to break out of, but you're not currently in a loop of that name, not even if you count where you were called from. See the last entry in the perlfunc manpage. (F) You named a loop to continue, but you're not currently in a loop of that name, not even if you count where you were called from. See the last entry in the perlfunc manpage. (F) You named a loop to restart, but you're not currently in a loop of that name, not even if you count where you were called from. See the last entry in the perlfunc manpage. (F) While under the "use filetest" pragma, switching the real and effective uids or gids failed. (W closed) You tried to do a listen on a closed socket. Did you forget to check the return value of your socket() call? See the listen entry in the perlfunc manpage. There is an upper limit to the depth of lookbehind in the (?<= regular expression construct. (F) Due to limitations in the current implementation, array and hash values cannot be returned in subroutines used in lvalue context. See the Lvalue subroutines entry in the perlsub manpage. (F) There is currently a limit on the length of string which lookbehind can handle. This restriction may be eased in a future release. The << HERE shows in the regular expression about where the problem was discovered. (F) An error peculiar to OS/2. PERLLIB_PREFIX should be of the form

    prefix1;prefix2
or

    prefix1 prefix2
with nonempty prefix1 and prefix2. If "prefix1" is indeed a prefix of a builtin library search path, prefix2 is substituted. The error may appear if components are not found, or are too long. See "PERLLIB_PREFIX" in the perlos2 manpage. Perl detected something that didn't comply with UTF-8 encoding rules. Perl thought it was reading UTF-16 encoded character data but while doing it Perl met a malformed Unicode surrogate. (W regexp) The pattern you've specified would be an infinite loop if the regular expression engine didn't specifically check for that. See the perlre manpage. (F) You can't pack a string by supplying a checksum, because the checksumming process loses information, and you can't go the other way. See the unpack entry in the perlfunc manpage. (F) An attempt was made to specify an entry in an overloading table that doesn't resolve to a valid subroutine. See the overload manpage. See Server error. (S) An advisory indicating that the previous error may have been caused by a missing delimiter on a string or pattern, because it eventually ended earlier on the current line. (W syntax) An underline in a decimal constant wasn't on a 3-digit boundary. (F) Wrong syntax of character name literal "\N{charname}" within double-quotish context. (F) While certain functions allow you to specify a filehandle or an "indirect object" before the argument list, this ain't one of them. (W pipe) You used the "open(FH, "| command")" or "open(FH, "command |")" construction, but the command was missing or blank. (F) The reserved syntax for lexically scoped subroutines requires that they have a name with which they can be found. (F) Apparently you've been programming in csh too much. Variables are always mentioned with the $ in Perl, unlike in the shells, where it can vary from one line to the next. (S) This is an educated guess made in conjunction with the message "%s found where operator expected". Often the missing operator is a comma. (F) The lexer counted more opening curly or square brackets than closing ones. As a general rule, you'll find it's missing near the place you were last editing. (S) This is an educated guess made in conjunction with the message "%s found where operator expected". Don't automatically put a semicolon on the previous line just because you saw this message. (F) You tried, directly or indirectly, to change the value of a constant. You didn't, of course, try "2 = 1", because the compiler catches that. But an easy way to do the same thing is:

    sub mod { $_[0] = 1 }
    mod(2);
Another way is to assign to a substr() that's off the end of the string.

Yet another way is to assign to a "foreach" loop VAR when VAR is aliased to a constant in the look LIST:

        $x = 1;
        foreach my $n ($x, 2) {
            $n *= 2; # modifies the $x, but fails on attempt to modify the 2
        }
(F) You tried to make an array value spring into existence, and the subscript was probably negative, even counting from end of the array backwards. (P) You tried to make a hash value spring into existence, and it couldn't be created for some peculiar reason. (F) Only a bare module name is allowed as the first argument to a "use". (F) The "-M" or "-m" options say that Perl should load some module, but you omitted the name of the module. Consult the perlrun manpage for full details about "-M" and "-m". (F) You don't have System V message IPC on your system. (W syntax) Multidimensional arrays aren't written like "$foo[1,2,3]". They're written like "$foo[1][2][3]", as in C. (F) You had a pack template indicating a counted-length string, Currently the only things that can have their length counted are a*, A* or Z*. See the pack entry in the perlfunc manpage. (F) You had an unpack template indicating a counted-length string, which must be followed by one of the letters a, A or Z to indicate what sort of string is to be unpacked. See the pack entry in the perlfunc manpage. (F) You had an unpack template that contained a '#', but this did not follow some numeric unpack specification. See the pack entry in the perlfunc manpage. (F) Lexically scoped subroutines are not yet implemented. Don't try that yet. (F) Lexically scoped variables aren't in a package, so it doesn't make sense to try to declare one with a package qualifier on the front. Use local() if you want to localize a package variable. (W once) Typographical errors often show up as unique variable names. If you had a good reason for having a unique name, then just mention it again somehow to suppress the message. The "our" declaration is provided for this purpose. (F) You tried to do a read/write/send/recv operation with a buffer length that is less than 0. This is difficult to imagine. (F) You can't quantify a quantifier without intervening parentheses. So things like ** or +* or ?* are illegal. The << HERE shows in the regular expression about where the problem was discovered.

Note, however, that the minimal matching quantifiers, "*?", "+?", and "??" appear to be nested quantifiers, but aren't. See the perlre manpage. (S internal) The symbol in question was declared but somehow went out of scope before it could possibly have been used. (F) Certain operations are deemed to be too insecure for a setuid or setgid script to even be allowed to attempt. Generally speaking there will be another way to do what you want that is, if not secure, at least securable. See the perlsec manpage. (F) A setuid script can't be specified by the user. (F) A list operator that has a filehandle or "indirect object" is not allowed to have a comma between that and the following arguments. Otherwise it'd be just another one of the arguments.

One possible cause for this is that you expected to have imported a constant to your name space with use or import while no such importing took place, it may for example be that your operating system does not support that particular constant. Hopefully you did use an explicit import list for the constants you expect to see, please see the use entry in the perlfunc manpage and the import entry in the perlfunc manpage. While an explicit import list would probably have caught this error earlier it naturally does not remedy the fact that your operating system still does not support that constant. Maybe you have a typo in the constants of the symbol import list of use or import or in the constant name at the line where this error was triggered? (F) An error peculiar to VMS. Perl handles its own command line redirection, and found a '|' at the end of the command line, so it doesn't know where you want to pipe the output from this command. (F) The currently executing code was compiled with the -d switch, but for some reason the perl5db.pl file (or some facsimile thereof) didn't define a routine to be called at the beginning of each statement. Which is odd, because the file should have been required automatically, and should have blown up the require if it didn't parse right. (P) This is counted as an internal error, because every machine should supply dbm nowadays, because Perl comes with SDBM. See the SDBM_File manpage. (F) The currently executing code was compiled with the -d switch, but for some reason the perl5db.pl file (or some facsimile thereof) didn't define a DB::sub routine to be called at the beginning of each ordinary subroutine call. (F) An error peculiar to VMS. Perl handles its own command line redirection, and found a '2>' or a '2>>' on the command line, but can't find the name of the file to which to write data destined for stderr. (F) An error peculiar to VMS. Perl handles its own command line redirection, and found a '<' on the command line, but can't find the name of the file from which to read data for stdin. (F) The setuid emulator requires that scripts have a well-formed #! line even on machines that don't support the #! construct. (F) The "no" keyword is recognized and executed at compile time, and returns no useful value. See the perlmod manpage. (F) An error peculiar to VMS. Perl handles its own command line redirection, and found a lone '>' at the end of the command line, so it doesn't know where you wanted to redirect stdout. (F) An error peculiar to VMS. Perl handles its own command line redirection, and found a '>' or a '>>' on the command line, but can't find the name of the file to which to write data destined for stdout. (F) Fully qualified variable names are not allowed in "our" declarations, because that doesn't make much sense under existing semantics. Such syntax is reserved for future extensions. (F) You called "perl -x", but no line was found in the file beginning with #! and containing the word "perl". (F) Configure didn't find anything resembling the setregid() call for your system. (F) Configure didn't find anything resembling the setreuid() call for your system. (F) The argument to the indicated command line switch must follow immediately after the switch, without intervening spaces. (F) The indicated command line switch needs a mandatory argument, but you haven't specified one. (P) An error peculiar to VMS. The internal routine my_pclose() tried to close a pipe which hadn't been opened. This should have been caught earlier as an attempt to close an unopened filehandle. (F) You tried to access an array as a hash, but the field name used is not defined. The hash at index 0 should map all valid field names to array indices for that to work. (F) You tried to access a field of a typed variable where the type does not know about the field name. The field names are looked up in the %FIELDS hash in the type package at compile time. The %FIELDS hash is %usually set up with the 'fields' pragma. (W signal) You specified a signal name as a subscript to %SIG that was not recognized. Say "kill -l" in your shell to see the valid signal names on your system. (F) Perl was trying to evaluate a reference to a code value (that is, a subroutine), but found a reference to something else instead. You can use the ref() function to find out what kind of ref it really was. See also the perlref manpage. (F) I'm not sure how you managed to generate a reference to an anonymous format, but this indicates you did, and that it didn't exist. (F) Perl was trying to evaluate a reference to a "typeglob" (that is, a symbol table entry that looks like "*foo"), but found a reference to something else instead. You can use the ref() function to find out what kind of ref it really was. See the perlref manpage. (F) Perl was trying to evaluate a reference to a hash value, but found a reference to something else instead. You can use the ref() function to find out what kind of ref it really was. See the perlref manpage. (F) Perl was trying to evaluate a reference to an array value, but found a reference to something else instead. You can use the ref() function to find out what kind of ref it really was. See the perlref manpage. (F) The setuid emulator requires that scripts have a well-formed #! line even on machines that don't support the #! construct. The line must mention perl. (F) Perl was trying to evaluate a reference to a scalar value, but found a reference to something else instead. You can use the ref() function to find out what kind of ref it really was. See the perlref manpage. (F) Perl was trying to evaluate a reference to a code value (that is, a subroutine), but found a reference to something else instead. You can use the ref() function to find out what kind of ref it really was. See also the perlref manpage. (F) An attempt was made to specify an entry in an overloading table that doesn't somehow point to a valid subroutine. See the overload manpage. (F) The function requires more arguments than you specified. (W syntax) A format specified more picture fields than the next line supplied. See the perlform manpage. (A) You've accidentally run your script through the Bourne shell instead of Perl. Check the #! line, or manually feed your script into Perl yourself. (S) A warning peculiar to VMS. Perl was unable to find the local timezone offset, so it's assuming that local system time is equivalent to UTC. If it's not, define the logical name SYS$TIMEZONE_DIFFERENTIAL to translate to the number of seconds which need to be added to UTC to get local time. (F) You can't require the null filename, especially because on many machines that means the current directory! See the require entry in the perlfunc manpage. (P debugging) Some internal routine called run() with a null opcode pointer. (F) The first argument to formline must be a valid format picture specification. It was found to be empty, which probably means you supplied it an uninitialized value. See the perlform manpage. (P) An attempt was made to realloc NULL. (P) The internal pattern matching routines blew it big time. (P) The internal pattern matching routines are out of their gourd. (F) Perl limits the representation of decimal numbers in programs to about about 250 characters. You've exceeded that length. Future versions of Perl are likely to eliminate this arbitrary limitation. In the meantime, try using scientific notation (e.g. "1e6" instead of "1_000_000"). (F) Numbers with a leading "0" are not currently allowed in vectors. The octal number interpretation of such numbers may be supported in a future version. (W portable) The octal number you specified is larger than 2**32-1 (4294967295) and therefore non-portable between systems. See the perlport manpage for more on portability concerns.

See also the perlport manpage for writing portable code. (W) The call to overload::constant contained an odd number of arguments. The arguments should come in pairs. (W misc) You specified an odd number of elements to initialize a hash, which is odd, because hashes come in key/value pairs. (F) You tried to do a read/write/send/recv operation with an offset pointing outside the buffer. This is difficult to imagine. The sole exception to this is that "sysread()"ing past the buffer will extend the buffer and zero pad the new area. (W unopened) You tried to invoke a file test operator on a filehandle that isn't open. Check your logic. See also the section on "-X" in the perlfunc manpage. (W unopened) An I/O operation was attempted on a filehandle that was never initialized. You need to do an open(), a sysopen(), or a socket() call, or call a constructor from the FileHandle package. (S internal) An internal warning that the grammar is screwed up. (S internal) An internal warning that the grammar is screwed up. (F) An attempt was made to perform an overloaded operation for which no handler was defined. While some handlers can be autogenerated in terms of other handlers, there is no default handler for any operation, unless "fallback" overloading key is specified to be true. See the overload manpage. (S ambiguous) You used a variable or subroutine call where the parser was expecting an operator. The parser has assumed you really meant to use an operator, but this is highly likely to be incorrect. For example, if you say "*foo *foo" it will be interpreted as if you said "*foo * 'foo'". (W misc) You seem to have already declared the same global once before in the current lexical scope. (X) The malloc() function returned 0, indicating there was insufficient remaining memory (or virtual memory) to satisfy the request. Perl has no option but to exit immediately. (F) The malloc() function returned 0, indicating there was insufficient remaining memory (or virtual memory) to satisfy the request. However, the request was judged large enough (compile-time default is 64K), so a possibility to shut down by trapping this error is granted. (X|F) The malloc() function returned 0, indicating there was insufficient remaining memory (or virtual memory) to satisfy the request.

The request was judged to be small, so the possibility to trap it depends on the way perl was compiled. By default it is not trappable. However, if compiled for this, Perl may use the contents of "$^M" as an emergency pool after die()ing with this message. In this case the error is trappable once, and the error message will include the line and file where the failed request happened. (F) You can't allocate more than 2^31+"small amount" bytes. This error is most likely to be caused by a typo in the Perl program. e.g., "$arr[time]" instead of "$arr[$time]". (F) The yacc parser wanted to grow its stack so it could continue parsing, but realloc() wouldn't give it more memory, virtual or otherwise. (F) You had a pack template that specified an absolute position outside the string being unpacked. See the pack entry in the perlfunc manpage. (W reserved) A lowercase attribute name was used that had a package-specific handler. That name might have a meaning to Perl itself some day, even though it doesn't yet. Perhaps you should use a mixed-case attribute name, instead. See the attributes manpage. (W io) A single call to write() produced more lines than can fit on a page. See the perlform manpage. (P) An internal error. (P) Failed an internal consistency check trying to compile a grep. (P) Failed an internal consistency check trying to compile a split. (P) The savestack was requested to restore more localized values than there are in the savestack. (P) Failed an internal consistency check while trying to reset a weak reference. (P) We popped the context stack to an eval context, and then discovered it wasn't an eval context. (P) The internal pp_match() routine was called with invalid operational data. (P) The internal pp_subst() routine was called with invalid operational data. (P) The internal do_trans routines were called with invalid operational data. (P) The library function frexp() failed, making printf("%f") impossible. (P) We popped the context stack to a context with the specified label, and then discovered it wasn't a context we know how to do a goto in. (P) The lexer got into a bad state at a case modifier. (P) The lexer got into a bad state parsing a string with brackets. (F) forked child returned an incomprehensible message about its errno. (P) We popped the context stack to a block context, and then discovered it wasn't a block context. (P) A writable lexical variable became read-only somehow within the scope. (P) The savestack probably got out of sync. At least, there was an invalid enum on the top of it. (P) Failed an internal consistency check while trying to reset all weak references to an object. (P) Something requested a negative number of bytes of malloc. (P) The compiler is screwed up with respect to the map() function. (P) One of the internal array routines was passed a null AV pointer. (P) The compiler got confused about which scratch pad it was allocating and freeing temporaries and lexicals from. (P) The compiler got confused about which scratch pad it was allocating and freeing temporaries and lexicals from. (P) An invalid scratch pad offset was detected internally. (P) The compiler got confused about which scratch pad it was allocating and freeing temporaries and lexicals from. (P) An invalid scratch pad offset was detected internally. (P) The compiler got confused about which scratch pad it was allocating and freeing temporaries and lexicals from. (P) An invalid scratch pad offset was detected internally. (P) The foreach iterator got called in a non-loop context frame. (P) Something terrible went wrong in setting up for the split. (P) Something requested a negative number of bytes of realloc. (P) Some internal routine requested a goto (or something like it), and didn't supply the destination. (P) We popped the context stack to a subroutine or eval context, and then discovered it wasn't a subroutine or eval context. (P) scan_num() got called on something that wasn't a number. (P) The sv_insert() routine was told to remove more string than there was string. (P) The compiler attempted to do a goto, or something weird like that. (P) The lexer got into a bad state while processing a case modifier. (P) Something tried to call utf16_to_utf8 with an odd (as opposed to even) byte length. (W parenthesis) You said something like

    my $foo, $bar = @_;
when you meant

    my ($foo, $bar) = @_;
Remember that "my", "our", and "local" bind tighter than comma. (F) The module in question uses features of a version of Perl more recent than the currently running version. How long has it been since you upgraded, anyway? See the require entry in the perlfunc manpage. (F) An error peculiar to OS/2. PERL_SH_DIR is the directory to find the "sh"-shell in. See "PERL_SH_DIR" in the perlos2 manpage. (S) The whole warning message will look something like:

        perl: warning: Setting locale failed.
        perl: warning: Please check that your locale settings:
                LC_ALL = "En_US",
                LANG = (unset)
            are supported and installed on your system.
        perl: warning: Falling back to the standard locale ("C").
Exactly what were the failed locale settings varies. In the above the settings were that the LC_ALL was "En_US" and the LANG had no value. This error means that Perl detected that you and/or your operating system supplier and/or system administrator have set up the so-called locale system but Perl could not use those settings. This was not dead serious, fortunately: there is a "default locale" called "C" that Perl can and will use, the script will be run. Before you really fix the problem, however, you will get the same error message each time you run Perl. How to really fix the problem can be found in the perllocale manpage section LOCALE PROBLEMS. (F) The setuid emulator in suidperl decided you were up to no good. (W exec) A warning peculiar to VMS. Waitpid() was asked to wait for a process which isn't a subprocess of the current process. While this is fine from VMS' perspective, it's probably not what you intended. (W unsafe) The character class constructs [: :], [= =], and [. .] go inside character classes, the [] are part of the construct, for example: /[012[:alpha:]345]/. Note that [= =] and [. .] are not currently implemented; they are simply placeholders for future extensions and will cause fatal errors. (F regexp) Within regular expression character classes ([]) the syntax beginning with "[." and ending with ".]" is reserved for future extensions. If you need to represent those character sequences inside a regular expression character class, just quote the square brackets with the backslash: "\[." and ".\]". (F) Within regular expression character classes ([]) the syntax beginning with "[=" and ending with "=]" is reserved for future extensions. If you need to represent those character sequences inside a regular expression character class, just quote the square brackets with the backslash: "\[=" and "=\]". (F) The class in the character class [: :] syntax is unknown. See the perlre manpage. (F) Your system has POSIX getpgrp(), which takes no argument, unlike the BSD version, which takes a pid. (W qw) qw() lists contain items separated by whitespace; as with literal strings, comment characters are not ignored, but are instead treated as literal data. (You may have used different delimiters than the parentheses shown here; braces are also frequently used.)

You probably wrote something like this:

    @list = qw(
        a # a comment
        b # another comment
    );
when you should have written this:

    @list = qw(
        a
        b
    );
If you really want comments, build your list the old-fashioned way, with quotes and commas:

    @list = (
        'a',    # a comment
        'b',    # another comment
    );
(W qw) qw() lists contain items separated by whitespace; therefore commas aren't needed to separate the items. (You may have used different delimiters than the parentheses shown here; braces are also frequently used.)

You probably wrote something like this:

    qw! a, b, c !;
which puts literal commas into some of the list items. Write it without commas if you don't want them to appear in your data:

    qw! a b c !;
(F) An ioctl() or fcntl() returned more than Perl was bargaining for. Perl guesses a reasonable buffer size, but puts a sentinel byte at the end of the buffer just in case. This sentinel byte got clobbered, and Perl assumes that memory is now corrupted. See the ioctl entry in the perlfunc manpage. (W y2k) You are concatenating the number 19 with another number, which could be a potential Year 2000 problem. (W deprecated) You have written something like this:

    sub doit
    {
        use attrs qw(locked);
    }
You should use the new declaration syntax instead.

    sub doit : locked
    {
        ...
The "use attrs" pragma is now obsolete, and is only provided for backward-compatibility. See the Subroutine Attributes entry in the perlsub manpage. (S precedence) The old irregular construct

    open FOO || die;
is now misinterpreted as

    open(FOO || die);
because of the strict regularization of Perl 5's grammar into unary and list operators. (The old open was a little of both.) You must put parentheses around the filehandle, or use the new "or" operator instead of "||". See Server error. (W closed) The filehandle you're writing to got itself closed sometime before now. Check your logic flow. (W closed) The filehandle you're printing on got itself closed sometime before now. Check your logic flow. (W) This is a standard message issued by OS/2 applications, while *nix applications die in silence. It is considered a feature of the OS/2 port. One can easily disable this by appropriate sighandlers, see the Signals entry in the perlipc manpage. See also "Process terminated by SIGTERM/SIGINT" in the perlos2 manpage. (S unsafe) The subroutine being declared or defined had previously been declared or defined with a different function prototype. (F) There is currently a limit to the size of the min and max values of the {min,max} construct. The << HERE shows in the regular expression about where the problem was discovered. See the perlre manpage. (W regexp) You applied a regular expression quantifier in a place where it makes no sense, such as on a zero-width assertion. Try putting the quantifier inside the assertion instead. For example, the way to match "abc" provided that it is followed by three repetitions of "xyz" is "/abc(?=(?:xyz){3})/", not "/abc(?=xyz){3}/". (F) One (or both) of the numeric arguments to the range operator ".." are outside the range which can be represented by integers internally. One possible workaround is to force Perl to use magical string increment by prepending "0" to your numbers. (W closed) The filehandle you're reading from got itself closed sometime before now. Check your logic flow. (F) You can't allocate more than 64K on an MS-DOS machine. (S malloc) An internal routine called realloc() on something that had already been freed. (F debugging) You can't use the -D option unless the code to produce the desired output is compiled into Perl, which entails some overhead, which is why it's currently left out of your copy. (F) More than 100 levels of inheritance were used. Probably indicates an unintended loop in your inheritance hierarchy. (F) More than 100 levels of inheritance were encountered while invoking a method. Probably indicates an unintended loop in your inheritance hierarchy. (W misc) You gave a single reference where Perl was expecting a list with an even number of elements (for assignment to a hash). This usually means that you used the anon hash constructor when you meant to use parens. In any case, a hash requires key/value pairs.

    %hash = { one => 1, two => 2, };    # WRONG
    %hash = [ qw/ an anon array / ];    # WRONG
    %hash = ( one => 1, two => 2, );    # right
    %hash = qw( one 1 two 2 );                  # also fine
(W misc) You have attempted to weaken a reference that is already weak. Doing so has no effect. (W internal) The internal sv_replace() function was handed a new SV with a reference count of other than 1. (F) You used something like "\7" in your regular expression, but there are not at least seven sets of capturing parentheses in the expression. If you wanted to have the character with value 7 inserted into the regular expression, prepend a zero to make the number at least two digits: "\07"

The << HERE shows in the regular expression about where the problem was discovered. (P) The regular expression engine got confused by what the regular expression compiler gave it. (P) A "can't happen" error, because safemalloc() should have caught it earlier. (F) You can't specify a repeat count so large that it overflows your signed integers. See the pack entry in the perlfunc manpage. (F) You can't specify a repeat count so large that it overflows your signed integers. See the unpack entry in the perlfunc manpage. (W syntax) You wrote your assignment operator backwards. The = must always comes last, to avoid ambiguity with subsequent unary operators. (F) Your format contained the ~~ repeat-until-blank sequence, but it produced 200 lines at once, and the 200th line looked exactly like the 199th line. Apparently you didn't arrange for the arguments to exhaust themselves, either by using ^ instead of @ (for scalar variables), or by shifting or popping (for array variables). See the perlform manpage. (W syntax) You've used an array slice (indicated by @) to select a single element of an array. Generally it's better to ask for a scalar value (indicated by $). The difference is that "$foo[&bar]" always behaves like a scalar, both when assigning to it and when evaluating its argument, while "@foo[&bar]" behaves like a list when you assign to it, and provides a list context to its subscript, which can do weird things if you're expecting only one subscript.

On the other hand, if you were actually hoping to treat the array element as a list, you need to look into how references work, because Perl will not magically convert between scalars and lists for you. See the perlref manpage. (W syntax) You've used a hash slice (indicated by @) to select a single element of a hash. Generally it's better to ask for a scalar value (indicated by $). The difference is that "$foo{&bar}" always behaves like a scalar, both when assigning to it and when evaluating its argument, while "@foo{&bar}" behaves like a list when you assign to it, and provides a list context to its subscript, which can do weird things if you're expecting only one subscript.

On the other hand, if you were actually hoping to treat the hash element as a list, you need to look into how references work, because Perl will not magically convert between scalars and lists for you. See the perlref manpage. (P) Something went wrong in Perl's internal bookkeeping of scalars: not all scalar variables were deallocated by the time Perl exited. What this usually indicates is a memory leak, which is of course bad, especially if the Perl program is intended to be long-running. (F) Oddly, the suidperl program was invoked on a script without a setuid or setgid bit set. This doesn't make much sense. (F) The lexer couldn't find the final delimiter of a // or m{} construct. Remember that bracketing delimiters count nesting level. Missing the leading "$" from a variable "$m" may cause this error. (W unopened) You tried to use the seek() or sysseek() function on a filehandle that was either never opened or has since been closed. (F) This machine doesn't implement the select() system call. (W semicolon) A nearby syntax error was probably caused by a missing semicolon, or possibly some other missing operator, such as a comma. (S internal) The internal newSVsv() routine was called to duplicate a scalar that had previously been marked as free. (F) You don't have System V semaphore IPC on your system. (W closed) The socket you're sending to got itself closed sometime before now. Check your logic flow. (F) A regular expression ended with an incomplete extension (?. The <<<HERE shows in the regular expression about where the problem was discovered. See the perlre manpage. (F) If the contents of a (?{...}) clause contains braces, they must balance for Perl to properly detect the end of the clause. See the perlre manpage. (F) A proposed regular expression extension has the character reserved but has not yet been written. The << HERE shows in the regular expression about where the problem was discovered. See the perlre manpage. (F) You used a regular expression extension that doesn't make sense. The << HERE shows in the regular expression about where the problem was discovered. See the perlre manpage. (F) A regular expression comment must be terminated by a closing parenthesis. Embedded parentheses aren't allowed. See the perlre manpage. See Server error. This is the error message generally seen in a browser window when trying to run a CGI program (including SSI) over the web. The actual error text varies widely from server to server. The most frequently-seen variants are "500 Server error", "Method (something) not permitted", "Document contains no data", "Premature end of script headers", and "Did not produce a valid header".

This is a CGI error, not a Perl error.

You need to make sure your script is executable, is accessible by the user CGI is running the script under (which is probably not the user account you tested it under), does not rely on any environment variables (like PATH) from the user it isn't running under, and isn't in a location where the CGI server can't find it, basically, more or less. Please see the following for more information:

        http://www.perl.com/CPAN/doc/FAQs/cgi/idiots-guide.html
        http://www.perl.com/CPAN/doc/FAQs/cgi/perl-cgi-faq.html
        ftp://rtfm.mit.edu/pub/usenet/news.answers/www/cgi-faq
        http://hoohoo.ncsa.uiuc.edu/cgi/interface.html
        http://www-genome.wi.mit.edu/WWW/faqs/www-security-faq.html
You should also look at the perlfaq9 manpage. (F) You tried to assign to "$)", and your operating system doesn't support the setegid() system call (or equivalent), or at least Configure didn't think so. (F) You tried to assign to "$>", and your operating system doesn't support the seteuid() system call (or equivalent), or at least Configure didn't think so. (F) Your system has the setpgrp() from BSD 4.2, which takes no arguments, unlike POSIX setpgid(), which takes a process ID and process group ID. (F) You tried to assign to "$(", and your operating system doesn't support the setrgid() system call (or equivalent), or at least Configure didn't think so. (F) You tried to assign to "$<", and your operating system doesn't support the setruid() system call (or equivalent), or at least Configure didn't think so. (W closed) You tried to set a socket option on a closed socket. Did you forget to check the return value of your socket() call? See the setsockopt entry in the perlfunc manpage. (F) The setuid emulator won't run a script that is writable by the world, because the world might have written on it already. (F) You don't have System V shared memory IPC on your system. (F) You wrote "require <file>" when you should have written "require 'file'". (W syntax) You have used a pattern where Perl expected to find a string, as in the first argument to "join". Perl will treat the true or false result of matching the pattern against $_ as the string, which is probably not what you had in mind. (W closed) You tried to do a shutdown on a closed socket. Seems a bit superfluous. (W signal) The signal handler named in %SIG doesn't, in fact, exist. Perhaps you put it into the wrong package? (F) An ancient error message that almost nobody ever runs into anymore. But before sort was a keyword, people sometimes used it as a filehandle. (F) A sort comparison routine must return a number. You probably blew it by not using "<=>" or "cmp", or by not using them correctly. See the sort entry in the perlfunc manpage. (F) A sort comparison subroutine may not return a list value with more or less than one element. See the sort entry in the perlfunc manpage. (P) The split was looping infinitely. (Obviously, a split shouldn't iterate more times than there are characters of input, which is what happened.) See the split entry in the perlfunc manpage. (W exec) You did an exec() with some statement after it other than a die(). This is almost always an error, because exec() never returns unless there was a failure. You probably wanted to use system() instead, which does return. To suppress this warning, put the exec() in a block by itself. (W unopened) You tried to use the stat() function on a filehandle that was either never opened or has since been closed. (P) Overloading resolution over @ISA tree may be broken by importation stubs. Stubs should never be implicitly created, but explicit calls to "can" may break this. (W redefine) You redefined a subroutine. To suppress this warning, say

    {
        no warnings;
        eval "sub name { ... }";
    }
(P) The substitution was looping infinitely. (Obviously, a substitution shouldn't iterate more times than there are characters of input, which is what happened.) See the discussion of substitution in the Quote and Quote-like Operators entry in the perlop manpage. (F) The lexer couldn't find the interior delimiter of a s/// or s{}{} construct. Remember that bracketing delimiters count nesting level. Missing the leading "$" from variable "$s" may cause this error. (F) The lexer couldn't find the final delimiter of a s/// or s{}{} construct. Remember that bracketing delimiters count nesting level. Missing the leading "$" from variable "$s" may cause this error. (W substr),(F) You tried to reference a substr() that pointed outside of a string. That is, the absolute value of the offset was larger than the length of the string. See the substr entry in the perlfunc manpage. This warning is fatal if substr is used in an lvalue context (as the left hand side of an assignment or as a subroutine argument for example). (F) Your Perl was compiled with -DSETUID_SCRIPTS_ARE_SECURE_NOW, but a version of the setuid emulator somehow got run anyway. (F) A (?(condition)if-clause|else-clause) construct can have at most two branches (the if-clause and the else-clause). If you want one or both to contain alternation, such as using "this|that|other", enclose it in clustering parentheses:

    (?(condition)(?:this|that|other)|else-clause)
The << HERE shows in the regular expression about where the problem was discovered. See the perlre manpage. (F) If the argument to the (?(...)if-clause|else-clause) construct is a number, it can be only a number. The << HERE shows in the regular expression about where the problem was discovered. See the perlre manpage. (F) While under the "use filetest" pragma, we cannot switch the real and effective uids or gids. (F) Probably means you had a syntax error. Common reasons include:

    A keyword is misspelled.
    A semicolon is missing.
    A comma is missing.
    An opening or closing parenthesis is missing.
    An opening or closing brace is missing.
    A closing quote is missing.
Often there will be another error message associated with the syntax error giving more information. (Sometimes it helps to turn on -w.) The error message itself often tells you where it was in the line when it decided to give up. Sometimes the actual error is several tokens before this, because Perl is good at understanding random input. Occasionally the line number may be misleading, and once in a blue moon the only way to figure out what's triggering the error is to call "perl -c" repeatedly, chopping away half the program each time to see if the error went away. Sort of the cybernetic version of 20 questions. (A) You've accidentally run your script through the Bourne shell instead of Perl. Check the #! line, or manually feed your script into Perl yourself. (F) The final summary message when a "perl -c" succeeds. (F) You tried to do something with a function beginning with "sem", "shm", or "msg" but that System V IPC is not implemented in your machine. In some machines the functionality can exist but be unconfigured. Consult your system support. (W closed) The filehandle you're writing to got itself closed sometime before now. Check your logic flow. (F) You tried to use "goto" to reach a label that was too deeply nested for Perl to reach. Perl is doing you a favor by refusing. (W unopened) You tried to use the tell() function on a filehandle that was either never opened or has since been closed. (F) Assignment to "$[" is now strictly circumscribed, and interpreted as a compiler directive. You may say only one of

    $[ = 0;
    $[ = 1;
    ...
    local $[ = 0;
    local $[ = 1;
    ...
This is to prevent the problem of one module changing the array base out from under another module inadvertently. See the section on "$[" in the perlvar manpage. (F) Configure couldn't find the crypt() function on your machine, probably because your vendor didn't supply it, probably because they think the U.S. Government thinks it's a secret, or at least that they will continue to pretend that it is. And if you quote me on that, I will deny it. The function indicated isn't implemented on this architecture, according to the probings of Configure. (F) It makes no sense to test the current stat buffer for symbolic linkhood if the last stat that wrote to the stat buffer already went past the symlink to get to the real file. Use an actual filename instead. (W internal) Warnings peculiar to VMS. You tried to change or delete an element of the CRTL's internal environ array, but your copy of Perl wasn't built with a CRTL that contained the setenv() function. You'll need to rebuild Perl with a CRTL that does, or redefine PERL_ENV_TABLES (see the perlvms manpage) so that the environ array isn't the target of the change to %ENV which produced the warning. (F) Your version of the C library apparently doesn't do times(). I suspect you're not running on Unix. (F) There has to be at least one argument to syscall() to specify the system call to call, silly dilly. (X) The #! line (or local equivalent) in a Perl script contains the -T option, but Perl was not invoked with -T in its command line. This is an error because, by the time Perl discovers a -T in a script, it's too late to properly taint everything from the environment. So Perl gives up.

If the Perl script is being executed as a command using the #! mechanism (or its local equivalent), this error can usually be fixed by editing the #! line so that the -T option is a part of Perl's first argument: e.g. change "perl -n -T" to "perl -T -n".

If the Perl script is being executed as "perl scriptname", then the -T option must appear on the command line: "perl -T scriptname". (X) The #! line (or local equivalent) in a Perl script contains the -M or -m option. This is an error because -M and -m options are not intended for use inside scripts. Use the "use" pragma instead. (W void) A CHECK or INIT block is being defined during run time proper, when the opportunity to run them has already passed. Perhaps you are loading a file with "require" or "do" when you should be using "use" instead. Or perhaps you should put the "require" or "do" inside a BEGIN block. (F) Perl supports a maximum of only 14 args to syscall(). (F) The function requires fewer arguments than you specified. (A) You've accidentally run your script through csh instead of Perl. Check the #! line, or manually feed your script into Perl yourself. (F) The regular expression ends with an unbackslashed backslash. Backslash it. See the perlre manpage. (F) The lexer couldn't find the interior delimiter of a tr/// or tr[][] or y/// or y[][] construct. Missing the leading "$" from variables "$tr" or "$y" may cause this error. (F) The lexer couldn't find the final delimiter of a tr/// or tr[][] construct. (F) Your machine doesn't implement a file truncation mechanism that Configure knows about. (F) This function requires the argument in that position to be of a certain type. Arrays must be @NAME or "@{EXPR}". Hashes must be %NAME or "%{EXPR}". No implicit dereferencing is allowed--use the {EXPR} forms as an explicit dereference. See the perlref manpage. (W umask) A umask of 222 is incorrect. It should be 0222, because octal literals always start with 0 in Perl, as in C. (F) Your machine doesn't implement the umask function and you tried to use it to restrict permissions for yourself (EXPR & 0700). (F) You attempted to create or access a subroutine with an illegal name. (W internal) The exit code detected an internal inconsistency in how many execution contexts were entered and left. (W internal) The exit code detected an internal inconsistency in how many values were temporarily localized. (W internal) The exit code detected an internal inconsistency in how many blocks were entered and left. (W internal) The exit code detected an internal inconsistency in how many mortal scalars were allocated and freed. (F) The format indicated doesn't seem to exist. Perhaps it's really in another package? See the perlform manpage. (F) The sort comparison routine specified doesn't seem to exist. Perhaps it's in a different package? See the sort entry in the perlfunc manpage. (F) The subroutine indicated hasn't been defined, or if it was, it has since been undefined. (F) The anonymous subroutine you're trying to call hasn't been defined, or if it was, it has since been undefined. (F) The sort comparison routine specified is declared but doesn't seem to have been defined yet. See the sort entry in the perlfunc manpage. (F) The format indicated doesn't seem to exist. Perhaps it's really in another package? See the perlform manpage. (W misc) An undefined value was assigned to a typeglob, a la "*foo = undef". This does nothing. It's possible that you really mean "undef *foo". (A) You've accidentally run your script through csh instead of Perl. Check the #! line, or manually feed your script into Perl yourself. (F) The unexec() routine failed for some reason. See your local FSF representative, who probably put it there in the first place. (F) There are no byte-swapping functions for a machine with this byte order. (F) The condition of a (?(condition)if-clause|else-clause) construct is not known. The condition may be lookaround (the condition is true if the lookaround is true), a (?{...}) construct (the condition is true if the code evaluates to a true value), or a number (the condition is true if the set of capturing parentheses named by the number is defined).

The << HERE shows in the regular expression about where the problem was discovered. See the perlre manpage. (F) The second argument of 3-argument open() is not among the list of valid modes: "<", ">", ">>", "+<", "+>", "+>>", "-|", "|-". (P) An error peculiar to VMS. Perl was reading values for %ENV before iterating over it, and someone else stuck a message in the stream of data Perl expected. Someone's very confused, or perhaps trying to subvert Perl's population of %ENV for nefarious purposes. (F) The brackets around a character class must match. If you wish to include a closing bracket in a character class, backslash it or put it first. See the perlre manpage. The << HERE shows in the regular expression about where the escape was discovered. (F) Unbackslashed parentheses must always be balanced in regular expressions. If you're a vi user, the % key is valuable for finding the matching parenthesis. See the perlre manpage. (F) The lexer counted more closing curly or square brackets than opening ones, so you're probably missing a matching opening bracket. As a general rule, you'll find the missing one (so to speak) near the place you were last editing. (W reserved) You used a bareword that might someday be claimed as a reserved word. It's best to put such a word in quotes, or capitalize it somehow, or insert an underbar into it. You might also declare it as a subroutine. (F) The Perl parser has no idea what to do with the specified character in your Perl script (or eval). Perhaps you tried to run a compressed script, a binary program, or a directory as a Perl program. (W regexp) You used a backslash-character combination which is not recognized by Perl inside character classes. The character was understood literally. (W regexp) You used a backslash-character combination which is not recognized by Perl. This combination appears in an interpolated variable or a "'"-delimited regular expression. The character was understood literally. The << HERE shows in the regular expression about where the escape was discovered. (W misc) You used a backslash-character combination which is not recognized by Perl. (F) You specified a signal name to the kill() function that was not recognized. Say "kill -l" in your shell to see the valid signal names on your system. (F) You specified an illegal option to Perl. Don't do that. (If you think you didn't do that, check the #! line to see if it's supplying the bad switch on your behalf.) (W newline) A file operation was attempted on a filename, and that operation failed, PROBABLY because the filename contained a newline, PROBABLY because you forgot to chomp() it off. See the chomp entry in the perlfunc manpage. (F) Your machine doesn't support opendir() and readdir(). (F) This machine doesn't implement the indicated function, apparently. At least, Configure doesn't think so. (F) Your version of executable does not support forking.

Note that under some systems, like OS/2, there may be different flavors of Perl executables, some of which may support fork, some not. Try changing the name you call Perl by to "perl_", "perl__", and so on. (F) Your program file begins with a Unicode Byte Order Mark (BOM) which declares it to be in a Unicode encoding that Perl cannot yet read. (F) Your machine doesn't support the Berkeley socket mechanism, or at least that's what Configure thought. (F) The lexer found something other than a simple identifier at the start of an attribute, and it wasn't a semicolon or the start of a block. Perhaps you terminated the parameter list of the previous attribute too soon. See the attributes manpage. (F) The lexer saw an opening (left) parenthesis character while parsing an attribute list, but the matching closing (right) parenthesis character was not found. You may need to add (or remove) a backslash character to get your parentheses to balance. See the attributes manpage. (F) An argument to unpack("w",...) was incompatible with the BER compressed integer format and could not be converted to an integer. See the pack entry in the perlfunc manpage. (F) The lexer saw a left angle bracket in a place where it was expecting a term, so it's looking for the corresponding right angle bracket, and not finding it. Chances are you left some needed parentheses out earlier in the line, and you really meant a "less than". (W untie) A copy of the object returned from "tie" (or "tied") was still valid when "untie" was called. (W void) You did something without a side effect in a context that does nothing with the return value, such as a statement that doesn't return a value from a block, or the left side of a scalar comma operator. Very often this points not to stupidity on your part, but a failure of Perl to parse your program the way you thought it would. For example, you'd get this if you mixed up your C precedence with Python precedence and said

    $one, $two = 1, 2;
when you meant to say

    ($one, $two) = (1, 2);
Another common error is to use ordinary parentheses to construct a list reference when you should be using square or curly brackets, for example, if you say

    $array = (1,2);
when you should have said

    $array = [1,2];
The square brackets explicitly turn a list value into a scalar value, while parentheses do not. So when a parenthesized list is evaluated in a scalar context, the comma is treated like C's comma operator, which throws away the left argument, which is not what you want. See the perlref manpage for more on this. (W) You did "use re;" without any arguments. That isn't very useful. (F) The "use" keyword is recognized and executed at compile time, and returns no useful value. See the perlmod manpage. (D deprecated) You are now encouraged to use the explicitly quoted form if you wish to use an empty line as the terminator of the here-document. (D deprecated) It makes a lot of work for the compiler when you clobber a subroutine's argument list, so it's better if you assign the results of a split() explicitly to an array (or list). (D deprecated) As an (ahem) accidental feature, "AUTOLOAD" subroutines are looked up as methods (using the "@ISA" hierarchy) even when the subroutines to be autoloaded were called as plain functions (e.g. "Foo::bar()"), not as methods (e.g. "Foo->bar()" or "$obj->bar()").

This bug will be rectified in future by using method lookup only for methods' "AUTOLOAD"s. However, there is a significant base of existing code that may be using the old behavior. So, as an interim step, Perl currently issues an optional warning when non-methods use inherited "AUTOLOAD"s.

The simple rule is: Inheritance will not work when autoloading non-methods. The simple fix for old code is: In any module that used to depend on inheriting "AUTOLOAD" for non-methods from a base class named "BaseClass", execute "*AUTOLOAD = \&BaseClass::AUTOLOAD" during startup.

In code that currently says "use AutoLoader; @ISA = qw(AutoLoader);" you should remove AutoLoader from @ISA and change "use AutoLoader;" to "use AutoLoader 'AUTOLOAD';". (F) You attempted to use a feature of printf that is accessible from only C. This usually means there's a better way to do it in Perl. (D deprecated) This variable magically turned on multi-line pattern matching, both for you and for any luckless subroutine that you happen to call. You should use the new "//m" and "//s" modifiers now to do that without the dangerous action-at-a-distance effects of "$*". (D deprecated) The construct indicated is no longer recommended for use, generally because there's a better way to do it, and also because the old way has bad side effects. (D deprecated) This was an ill-advised attempt to emulate a poorly defined awk feature. Use an explicit printf() or sprintf() instead. (D deprecated) The indicated bareword is a reserved word. Future versions of perl may use it as a keyword, so you're better off either explicitly quoting the word in a manner appropriate for its context of use, or using a different name altogether. The warning can be suppressed for subroutine names by either adding a "&" prefix, or using a package qualifier, e.g. "&our()", or "Foo::our()". (W uninitialized) An undefined value was used as if it were already defined. It was interpreted as a "" or a 0, but maybe it was a mistake. To suppress this warning assign a defined value to your variables.

To help you figure out what was undefined, perl tells you what operation you used the undefined value in. Note, however, that perl optimizes your program and the operation displayed in the warning may not necessarily appear literally in your program. For example, ""that $foo"" is usually optimized into ""that " . $foo", and the warning will refer to the "concatenation (.)" operator, even though there is no "." in your program. (W misc) In a conditional expression, you used <HANDLE>, <*> (glob), "each()", or "readdir()" as a boolean value. Each of these constructs can return a value of "0"; that would make the conditional expression false, which is probably not what you intended. When using these constructs in conditional expressions, test their values with the "defined" operator. (W misc) A warning peculiar to VMS. Perl tried to read the value of an %ENV element from a CLI symbol table, and found a resultant string longer than 1024 characters. The return value has been truncated to 1024 characters. (F) While "use strict" in effect, you referred to a global variable that you apparently thought was imported from another module, because something else of the same name (usually a subroutine) is exported by that module. It usually means you put the wrong funny character on the front of your variable. (W misc) A "my" or "our" variable has been redeclared in the current scope or statement, effectively eliminating all access to the previous instance. This is almost always a typographical error. Note that the earlier variable will still exist until the end of the scope or until all closure referents to it are destroyed. (W closure) An inner (nested) anonymous subroutine is inside a named subroutine, and outside that is another subroutine; and the anonymous (innermost) subroutine is referencing a lexical variable defined in the outermost subroutine. For example:

   sub outermost { my $a; sub middle { sub { $a } } }
If the anonymous subroutine is called or referenced (directly or indirectly) from the outermost subroutine, it will share the variable as you would expect. But if the anonymous subroutine is called or referenced when the outermost subroutine is not active, it will see the value of the shared variable as it was before and during the *first* call to the outermost subroutine, which is probably not what you want.

In these circumstances, it is usually best to make the middle subroutine anonymous, using the "sub {}" syntax. Perl has specific support for shared variables in nested anonymous subroutines; a named subroutine in between interferes with this feature. (A) You've accidentally run your script through csh instead of Perl. Check the #! line, or manually feed your script into Perl yourself. (W closure) An inner (nested) named subroutine is referencing a lexical variable defined in an outer subroutine.

When the inner subroutine is called, it will probably see the value of the outer subroutine's variable as it was before and during the *first* call to the outer subroutine; in this case, after the first call to the outer subroutine is complete, the inner and outer subroutines will no longer share a common value for the variable. In other words, the variable will no longer be shared.

Furthermore, if the outer subroutine is anonymous and references a lexical variable outside itself, then the outer and inner subroutines will never share the given variable.

This problem can usually be solved by making the inner subroutine anonymous, using the "sub {}" syntax. When inner anonymous subs that reference variables in outer subroutines are called or referenced, they are automatically rebound to the current values of such variables. (F) Lookbehind is allowed only for subexpressions whose length is fixed and known at compile time. The << HERE shows in the regular expression about where the problem was discovered. (P) The attempt to translate a "use Module n.n LIST" statement into its equivalent "BEGIN" block found an internal inconsistency with the version number. (W) You passed warn() an empty string (the equivalent of "warn """) or you called it with no args and "$_" was empty. (S) The implicit close() done by an open() got an error indication on the close(). This usually indicates your file system ran out of disk space. (S ambiguous) You wrote a unary operator followed by something that looks like a binary operator that could also have been interpreted as a term or unary operator. For instance, if you know that the rand function has a default argument of 1.0, and you write

    rand + 5;
you may THINK you wrote the same thing as

    rand() + 5;
but in actual fact, you got

    rand(+5);
So put in parentheses to say what you really mean. (F) Perl met a wide character (>255) when it wasn't expecting one. (W closed) The filehandle you're writing to got itself closed sometime before now. Check your logic flow. (F) You had a pack template that specified a relative position before the beginning of the string being unpacked. See the pack entry in the perlfunc manpage. (F) You had a pack template that specified a relative position after the end of the string being unpacked. See the pack entry in the perlfunc manpage. (F) The use of an external subroutine as a sort comparison is not yet supported. (F) The use of an external subroutine as a sort comparison is not yet supported. (F) A filehandle represents an opened file, and when you opened the file it already went past any symlink you are presumably trying to look for. Use a filename instead. (F) And you probably never will, because you probably don't have the sources to your kernel, and your vendor probably doesn't give a rip about what you want. Your best bet is to use the wrapsuid script in the eg directory to put a setuid C wrapper around your script. (W syntax) You assigned a bareword as a signal handler name. Unfortunately, you already have a subroutine of that name declared, which means that Perl 5 will try to call the subroutine when the assignment is executed, which is probably not what you want. (If it IS what you want, put an & in front.)