### 34.2 Filesystem Utilities

Octave includes the following functions for renaming and deleting files, creating, deleting, and reading directories, and for getting information about the status of files.

— Built-in Function: [err, msg] = rename (old, new)

> Change the name of file old to new.

> If successful, err is 0 and msg is an empty string. Otherwise, err is nonzero and msg contains a system-dependent error message.

— Built-in Function: [err, msg] = link (old, new)

> Create a new link (also known as a hard link) to an existing file.

> If successful, err is 0 and msg is an empty string. Otherwise, err is nonzero and msg contains a system-dependent error message.

— Built-in Function: [err, msg] = symlink (old, new)

> Create a symbolic link new which contains the string old.

> If successful, err is 0 and msg is an empty string. Otherwise, err is nonzero and msg contains a system-dependent error message.

— Built-in Function: [result, err, msg] = readlink (symlink)

> Read the value of the symbolic link symlink.

> If successful, result contains the contents of the symbolic link symlink, err is 0 and msg is an empty string. Otherwise, err is nonzero and msg contains a system-dependent error message.

— Built-in Function: [err, msg] = unlink (file)

> Delete the file named file.

> If successful, err is 0 and msg is an empty string. Otherwise, err is nonzero and msg contains a system-dependent error message.

— Built-in Function: [files, err, msg] = readdir (dir)

> Return names of the files in the directory dir as a cell array of strings. If an error occurs, return an empty cell array in files.

> If successful, err is 0 and msg is an empty string. Otherwise, err is nonzero and msg contains a system-dependent error message.

— Built-in Function: [err, msg] = mkdir (dir)

> Create a directory named dir.

> If successful, err is 0 and msg is an empty string. Otherwise, err is nonzero and msg contains a system-dependent error message.

— Built-in Function: [err, msg] = rmdir (dir)

> Remove the directory named dir.

> If successful, err is 0 and msg is an empty string. Otherwise, err is nonzero and msg contains a system-dependent error message.

— Built-in Function: [err, msg] = mkfifo (name, mode)

> Create a fifo special file named name with file mode mode

> If successful, err is 0 and msg is an empty string. Otherwise, err is nonzero and msg contains a system-dependent error message.

— Built-in Function: umask (mask)

> Set the permission mask for file creation. The parameter mask is an integer, interpreted as an octal number. If successful, returns the previous value of the mask (as an integer to be interpreted as an octal number); otherwise an error message is printed.

— Built-in Function: [info, err, msg] = stat (file)
— Built-in Function: [info, err, msg] = lstat (file)

> Return a structure s containing the following information about file.

> `dev`
>   ID of device containing a directory entry for this file.
> `ino`
>   File number of the file.
> `modestr`
>   File mode, as a string of ten letters or dashes as would be returned by `ls -l`.
> `nlink`
>   Number of links.
> `uid`
>   User ID of file's owner.
> `gid`
>   Group ID of file's group.
> `rdev`
>   ID of device for block or character special files.
> `size`
>   Size in bytes.
> `atime`
>   Time of last access in the same form as time values returned from `time`. See Timing Utilities.
> `mtime`
>   Time of last modification in the same form as time values returned from `time`. See Timing Utilities.
> `ctime`
>   Time of last file status change in the same form as time values returned from `time`. See Timing Utilities.
> `blksize`
>   Size of blocks in the file.
> `blocks`
>   Number of blocks allocated for file.

> If the call is successful err is 0 and msg is an empty string. If the file does not exist, or some other error occurs, s is an empty matrix, err is −1, and msg contains the corresponding system error message.

> If file is a symbolic link, `stat` will return information about the actual file the is referenced by the link. Use `lstat` if you want information about the symbolic link itself.

> For example,

>               [s, err, msg] = stat ("/vmlinuz")
>                     => s =
>                       {
>                         atime = 855399756
>                         rdev = 0
>                         ctime = 847219094
>                         uid = 0
>                         size = 389218
>                         blksize = 4096
>                         mtime = 847219094
>                         gid = 6
>                         nlink = 1
>                         blocks = 768
>                         modestr = -rw-r--r--
>                         ino = 9316
>                         dev = 2049
>                       }
>                    => err = 0
>                    => msg =

— Built-in Function: glob (pattern)

> Given an array of strings in pattern, return a cell array of file names that match any of them, or an empty cell array if no patterns match. Tilde expansion is performed on each of the patterns before looking for matching file names. For example,

>               glob ("/vm*")
>                    => "/vmlinuz"

— Built-in Function: fnmatch (pattern, string)

> Return 1 or zero for each element of string that matches any of the elements of the string array pattern, using the rules of filename pattern matching. For example,

>               fnmatch ("a*b", ["ab"; "axyzb"; "xyzab"])
>                    => [ 1; 1; 0 ]

— Built-in Function: file_in_path (path, file)
— Built-in Function: file_in_path (path, file, "all")

> Return the absolute name name of file if it can be found in path. The value of path should be a colon-separated list of directories in the format described for the built-in variable `LOADPATH`. If no file is found, return an empty matrix. For example,

>               file_in_path (LOADPATH, "nargchk.m")
>                    => "/usr/local/share/octave/2.0/m/general/nargchk.m"

> If the second argument is a cell array of of strings, search each directory of the path for element of the cell array and return the first that matches.

> If the third optional argument `"all"` is supplied, return a cell array containing the list of all files that have the same name in the path. If no files are found, return an empty cell array.

— Built-in Function: tilde_expand (string)

> Performs tilde expansion on string. If string begins with a tilde character, (``~`'), all of the characters preceding the first slash (or all characters, if there is no slash) are treated as a possible user name, and the tilde and the following characters up to the slash are replaced by the home directory of the named user. If the tilde is followed immediately by a slash, the tilde is replaced by the home directory of the user running Octave. For example,

>               tilde_expand ("~joeuser/bin")
>                    => "/home/joeuser/bin"
>               tilde_expand ("~/bin")
>                    => "/home/jwe/bin"