# Unit files

This unit contains file- and pathname-oriented procedures. It uses the `regex` unit.

## Pathname operations

### absolute-pathname?

     [procedure] (absolute-pathname? PATHNAME)

Returns `#t` if the string `PATHNAME` names an absolute pathname, and returns `#f` otherwise.

### decompose-pathname

     [procedure] (decompose-pathname PATHNAME)

Returns three values: the directory-, filename- and extension-components of the file named by the string `PATHNAME`. For any component that is not contained in `PATHNAME`, `#f` is returned.

### make-pathname

### make-absolute-pathname

     [procedure] (make-pathname DIRECTORY FILENAME [EXTENSION [SEPARATOR]])

     [procedure] (make-absolute-pathname DIRECTORY FILENAME [EXTENSION [SEPARATOR]])

Returns a string that names the file with the components `DIRECTORY, FILENAME` and (optionally) `EXTENSION` with `SEPARATOR` being the directory separation indicator (usually `/` on UNIX systems and `\` on Windows, defaulting to whatever platform this is running on). `DIRECTORY` can be `#f` (meaning no directory component), a string or a list of strings. `FILENAME` and `EXTENSION` should be strings or `#f`. `make-absolute-pathname` returns always an absolute pathname.

### pathname-directory

     [procedure] (pathname-directory PATHNAME)

### pathname-file

     [procedure] (pathname-file PATHNAME)

### pathname-extension

     [procedure] (pathname-extension PATHNAME)

Accessors for the components of `PATHNAME`. If the pathname does not contain the accessed component, then `#f` is returned.

### pathname-replace-directory

     [procedure] (pathname-replace-directory PATHNAME DIRECTORY)

### pathname-replace-file

     [procedure] (pathname-replace-file PATHNAME FILENAME)

### pathname-replace-extension

     [procedure] (pathname-replace-extension PATHNAME EXTENSION)

Return a new pathname with the specified component of `PATHNAME` replaced by a new value.

### pathname-strip-directory

     [procedure] (pathname-strip-directory PATHNAME)

### pathname-strip-extension

     [procedure] (pathname-strip-extension PATHNAME)

Return a new pathname with the specified component of `PATHNAME` stripped.

### normalize-pathname

     [procedure] (normalize-pathname PATHNAME [PLATFORM])

Performs a simple "normalization" on the `PATHNAME`, suitably for `PLATFORM`, which should be one of the symbols `windows` or `unix` and defaults to on whatever platform is currently in use. All relative path elements and duplicate separators are processed and removed. If `NAME` ends with a `/` or is empty, the appropriate slash is appended to the tail. Tilde `~` and variable `$<name>/...` expansion is also done.
No directories or files are actually tested for existence; this procedure only canonicalises path syntax.

### directory-null?

     [procedure] (directory-null? DIRECTORY)

Does the `DIRECTORY` consist only of path separators and the period?
`DIRECTORY` may be a string or a list of strings.

## Temporary files

### create-temporary-file

     [procedure] (create-temporary-file [EXTENSION])

Creates an empty temporary file and returns its pathname. If `EXTENSION` is not given, then `.tmp` is used. If the environment variable `TMPDIR, TEMP` or `TMP` is set, then the pathname names a file in that directory.

## Deleting a file without signalling an error

### delete-file*

     [procedure] (delete-file* FILENAME)

If the file `FILENAME` exists, it is deleted and `#t` is returned. If the file does not exist, nothing happens and `#f` is returned.

## File move/copy

### file-copy

     [procedure] (file-copy ORIGFILE NEWFILE #!optional CLOBBER BLOCKSIZE)

Copies `ORIGFILE` (a string denoting some filename) to `NEWFILE`, `BLOCKSIZE` bytes at a time. `BLOCKSIZE` defaults to 1024, and must be a positive integer. Returns the number of bytes copied on success, or errors on failure. `CLOBBER` determines the behaviour of `file-copy` when `NEWFILE` is already extant. When set to `#f` (default), an error is signalled. When set to any other value, `NEWFILE` is overwritten. `file-copy` will work across filesystems and devices and is not platform-dependent.

### file-move

     [procedure] (file-move ORIGFILE NEWFILE #!optional CLOBBER BLOCKSIZE)

Moves `ORIGFILE` (a string denoting some filename) to `NEWFILE`, with the same semantics as `file-copy`, above. `file-move` is safe across filesystems and devices (unlike `file-rename`). It is possible for an error to be signalled despite partial success if `NEWFILE` could be created and fully written but removing `ORIGFILE` fails.

Previous: Unit ports
Next: Unit extras