## SYNOPSIS

           a2p [options] filename

## DESCRIPTION

           A2p takes an awk script specified on the command line (or
           from standard input) and produces a comparable perl script
           on the standard output.

           Options

           Options include:

           -D<number>
                sets debugging flags.

           -F<character>
                tells a2p that this awk script is always invoked with
                this -F switch.

           -n<fieldlist>
                specifies the names of the input fields if input does
                not have to be split into an array.  If you were
                translating an awk script that processes the password
                file, you might say:

                        a2p -7 -nlogin.password.uid.gid.gcos.shell.home

                Any delimiter can be used to separate the field
                names.

           -<number>
                causes a2p to assume that input will always have that
                many fields.

           -o   tells a2p to use old awk behavior.  The only current
                differences are:

                ·    Old awk always has a line loop, even if there
                     are no line actions, whereas new awk does not.

                ·    In old awk, sprintf is extremely greedy about
                     its arguments.  For example, given the statement

                             print sprintf(some_args), extra_args;

                     old awk considers extra_args to be arguments to
                     "sprintf"; new awk considers them arguments to
                     "print".

           "Considerations"

           A2p cannot do as good a job translating as a human would,
           time which comparison to do.  A2p does not try to do a
           complete job of awk emulation at this point.  Instead it
           guesses which one you want.  It's almost always right, but
           it can be spoofed.  All such guesses are marked with the
           comment ""#???"".  You should go through and check them.
           You might want to run at least once with the -w switch to
           perl, which will warn you if you use == where you should
           have used eq.

           Perl does not attempt to emulate the behavior of awk in
           which nonexistent array elements spring into existence
           simply by being referenced.  If somehow you are relying on
           this mechanism to create null entries for a subsequent
           for...in, they won't be there in perl.

           If a2p makes a split line that assigns to a list of vari
           ables that looks like (Fld1, Fld2, Fld3...) you may want
           to rerun a2p using the -n option mentioned above.  This
           will let you name the fields throughout the script.  If it
           splits to an array instead, the script is probably refer
           ring to the number of fields somewhere.

           The exit statement in awk doesn't necessarily exit; it
           goes to the END block if there is one.  Awk scripts that
           do contortions within the END block to bypass the block
           under such circumstances can be simplified by removing the
           conditional in the END block and just exiting directly
           from the perl script.

           Perl has two kinds of array, numerically-indexed and asso
           ciative.  Perl associative arrays are called "hashes".
           Awk arrays are usually translated to hashes, but if you
           happen to know that the index is always going to be
           numeric you could change the {...} to [...].  Iteration
           over a hash is done using the keys() function, but itera
           tion over an array is NOT.  You might need to modify any
           loop that iterates over such an array.

           Awk starts by assuming OFMT has the value %.6g.  Perl
           starts by assuming its equivalent, $#, to have the value
           %.20g.  You'll want to set $# explicitly if you use the
           default value of OFMT.

           Near the top of the line loop will be the split operation
           that is implicit in the awk script.  There are times when
           you can move this down past some conditionals that test
           the entire record so that the split is not done as often.

           For aesthetic reasons you may wish to change the array
           base $[ from 1 back to perl's default of 0, but remember
           to change all array subscripts AND all substr() and
           index() operations to match.

           The produced perl script may have subroutines defined to
           deal with awk's semantics regarding getline and print.
           Since a2p usually picks correctness over efficiency.  it
           is almost always possible to rewrite such code to be more
           efficient by discarding the semantic sugar.

           For efficiency, you may wish to remove the keyword from
           any return statement that is the last statement executed
           in a subroutine.  A2p catches the most common case, but
           doesn't analyze embedded blocks for subtler cases.

           ARGV[0] translates to $ARGV0, but ARGV[n] translates to
           $ARGV[$n].  A loop that tries to iterate over ARGV[0]
           won't find it.

## ENVIRONMENT

           A2p uses no environment variables.

## AUTHOR

           Larry Wall <larry@wall.org>

## FILES

## SEE ALSO

            perl   The perl compiler/interpreter

            s2p    sed to perl translator

## DIAGNOSTICS

## BUGS

           It would be possible to emulate awk's behavior in select
           ing string versus numeric operations at run time by
           inspection of the operands, but it would be gross and
           inefficient.  Besides, a2p almost always guesses right.

           Storage for the awk syntax tree is currently static, and
           can run out.

    perl v5.8.0                 2002-06-01                     A2P(1)