File system operations Isis software documentation

File system operations

This document explains the file system manipulation utilities in Isis, including routines for reading directories and obtaining information about disk files. For information about how to access the data in disk files, see the input and output ports documentation.

Basic file system utilities

(remove-file filename) # permanently remove a disk file (rename-file fromfilename tofilename) # rename a disk file (copy-file fromfilename tofilename) # copy a disk file (create-directory dirname) # create a new directory (read-directory) # read current directory, return list of filenames (read-directory dirname) # read the named directory You can remove, rename, and copy disk files using the first three functions listed above. create-directory creates a new directory in the file system at the given location. These four routines return True if successful or False if not.

read-directory returns a list of string file names in the directory specified, or the current working directory if no argument is passed, otherwise it returns Null if there was an error. This listing will include the current (.) and parent (..) directories.

-> (read-directory) [ "." ".." "fontgentest.isis" "fonttest.isis" "makefonts.isis" "viewfonts.isis" ]

File information

(file-accessible? filename) # return True if file exists and is accessible, otherwise False (file-size filename) # return size of file in bytes, or Null if error (file-type filename) # return type of file, or Null if error (file-info filename) # return list of file information (see below) These routines can be used to get information about files in the file system. file-type will return a value that matches one of these pre-defined constants: file-type-regular file-type-directory file-type-block file-type-character file-type-fifo file-info returns a long list of information about a specified file, or Null if there is an error. You can extract the information you need by indexing into this list with the pre-defined constants shown below: file-info-type # matches one of the file types shown above file-info-size # size in bytes file-info-user-read # permissions are either True or False file-info-user-write file-info-user-execute file-info-group-read file-info-group-write file-info-group-execute file-info-other-read file-info-other-write file-info-other-execute file-info-user-id # id of file owner file-info-set-user-id file-info-group-id file-info-set-group-id file-info-last-access # times are in seconds since jan 1 1970 file-info-last-modification file-info-last-status-change The following example shows how to find the size and write permission status of a file garb.c:
(set garbinfo (file-info "garb.c")) (set garbsize (garbinfo file-info-size)) (set garbwriteperm (garbinfo file-info-user-write))