Chapter 20. Files
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Chapter 20. Files [chap-20]

Directory is not a file

CLISP has traditionally taken the view that a directory is a separate object and not a special kind of file, so whenever the standard says that a function operates on files without specifically mentioning that it also works on directories, CLISP SIGNALs an ERROR when passed a directory.

CLISP provides separate directory functions, such as EXT:DELETE-DIRECTORY, EXT:RENAME-DIRECTORY et al.

Function PROBE-FILE

PROBE-FILE cannot be used to check whether a directory exists. Use functions EXT:PROBE-DIRECTORY or DIRECTORY for this.

Function FILE-AUTHOR

FILE-AUTHOR always returns NIL, because the operating systems CLISP is ported to do not store a file's author in the file system. Some operating systems, such as UNIX, have the notion of a file's owner, and some other Common Lisp implementations return the user name of the file owner. CLISP does not do this, because owner and author are not the same; in particular, authorship is preserved by copying, while ownership is not.

Use OS:FILE-OWNER to find the owner of the file. See also OS:FILE-PROPERTIES (Platform Dependent: Win32 platform only.).

Function EXT:PROBE-DIRECTORY

(EXT:PROBE-DIRECTORY pathname) tests whether pathname exists and is a directory. It will, unlike PROBE-FILE or TRUENAME, not SIGNAL an ERROR if the parent directory of pathname does not exist.

Function DELETE-FILE

(DELETE-FILE pathname) deletes the pathname pathname, not its TRUENAME, and returns the absolute pathname it actually removed or NIL if pathname did not exist. When pathname points to a file which is currently open in CLISP, an ERROR is SIGNALed. To remove a directory, use EXT:DELETE-DIRECTORY instead.

Function RENAME-FILE

This function cannot operate on directories, use EXT:RENAME-DIRECTORY to rename a directory.

Function DIRECTORY

(DIRECTORY &OPTIONAL pathname &KEY :FULL :CIRCLE :IF-DOES-NOT-EXIST) can run in two modes:

  • If pathname contains no name or type component, a list of all matching directories is produced. E.g., (DIRECTORY "/etc/*/") lists all subdirectories in the directory #P"/etc/".
  • Otherwise a list of all matching files is returned. E.g., (DIRECTORY "/etc/*") lists all regular files in the directory #P"/etc/". If the :FULL argument is non-NIL, additional information is returned: for each matching file you get a LIST of at least four elements (file-pathname file-truename file-write-date-as-decoded-time file-length).

If you want all the files and subdirectories in the current directory, you should use (NCONC (DIRECTORY "*/") (DIRECTORY "*")). If you want all the files and subdirectories in all the subdirectories under the current directory (similar to the ls -R UNIX command), use (NCONC (DIRECTORY "**/") (DIRECTORY "**/*")). [an error occurred while processing this directive]