APP_USER_DIR - Provides access to the application user directory.
APP_USER_DIR_QUERY - Locates existing application user directories.
CALL_EXTERNAL - Calls a function in an external sharable object and returns a scalar value.
CD - Sets and/or changes the current working directory.
FILE_CHMOD - Changes file access permissions.
FILE_DELETE - Deletes files and empty directories.
FILE_EXPAND_PATH - Fully qualifies file and directory paths.
FILE_INFO - Returns status information about a file.
FILE_MKDIR - Creates directories.
FILE_SAME - Determines whether two different file names refer to the same underlying file.
FILE_SEARCH - Returns a string array containing the names of all files matching the input path specification.
FILE_TEST - Test a file or directory for existence and other specific attributes.
FILE_WHICH - Searches for a specified file in a directory search path.
GET_DRIVE_LIST (Windows only) - Returns string array of the names of valid drives/volumes for the file system.
GET_SCREEN_SIZE - Returns dimensions of the screen.
GETENV - Returns the value of an environment variable.
LINKIMAGE - Merges routines written in other languages with IDL at run-time.
PATH_SEP - Returns the proper file path segment separator character for the current operating system.
POPD - Removes the top directory on the working directory stack maintained by PUSHD/POPD.
PRINTD - Prints contents of the directory stack maintained by PUSHD/POPD.
PUSHD - Pushes a directory to top of directory stack maintained by PUSHD/POPD.
SETENV - Adds or changes an environment variable.
SETUP_KEYS - Sets function keys for UNIX versions of IDL.
SPAWN - Spawns child process for access to operating system.