(octave.info)Temporary Files

---

Next: EOF and Errors Prev: Binary I/O Up: C-Style I/O Functions

---

Enter node , (file) or (file)node

14.2.17 Temporary Files
-----------------------

Sometimes one needs to write data to a file that is only temporary.
This is most commonly used when an external program launched from within
Octave needs to access data.  When Octave exits all temporary files will
be deleted, so this step need not be executed manually.

 -- : [FID, NAME, MSG] = mkstemp ("TEMPLATE")
 -- : [FID, NAME, MSG] = mkstemp ("TEMPLATE", DELETE)
     Return the file descriptor FID corresponding to a new temporary
     file with a unique name created from TEMPLATE.

     The last six characters of TEMPLATE must be "XXXXXX" and these are
     replaced with a string that makes the filename unique.  The file is
     then created with mode read/write and permissions that are system
     dependent (on GNU/Linux systems, the permissions will be 0600 for
     versions of glibc 2.0.7 and later).  The file is opened in binary
     mode and with the ‘O_EXCL’ flag.

     If the optional argument DELETE is supplied and is true, the file
     will be deleted automatically when Octave exits.

     If successful, FID is a valid file ID, NAME is the name of the
     file, and MSG is an empty string.  Otherwise, FID is -1, NAME is
     empty, and MSG contains a system-dependent error message.

     See also: Note: tempname, Note: tempdir,
     Note: P_tmpdir, Note: tmpfile, Note:
     fopen.

 -- : [FID, MSG] = tmpfile ()
     Return the file ID corresponding to a new temporary file with a
     unique name.

     The file is opened in binary read/write ("w+b") mode and will be
     deleted automatically when it is closed or when Octave exits.

     If successful, FID is a valid file ID and MSG is an empty string.
     Otherwise, FID is -1 and MSG contains a system-dependent error
     message.

     See also: Note: tempname, Note: mkstemp,
     Note: tempdir, Note: P_tmpdir.

 -- : FNAME = tempname ()
 -- : FNAME = tempname (DIR)
 -- : FNAME = tempname (DIR, PREFIX)
     Return a unique temporary filename as a string.

     If PREFIX is omitted, a value of "oct-" is used.

     If DIR is also omitted, the default directory for temporary files
     (‘P_tmpdir’) is used.  If DIR is provided, it must exist, otherwise
     the default directory for temporary files is used.

     Programming Note: Because the named file is not opened by
     ‘tempname’, it is possible, though relatively unlikely, that it
     will not be available by the time your program attempts to open it.
     If this is a concern, see ‘tmpfile’.

     See also: Note: mkstemp, Note: tempdir,
     Note: P_tmpdir, Note: tmpfile.

 -- : DIR = tempdir ()
     Return the name of the host system’s directory for temporary files.

     The directory name is taken first from the environment variable
     ‘TMPDIR’.  If that does not exist the system default returned by
     ‘P_tmpdir’ is used.

     See also: Note: P_tmpdir, *note tempname:
     XREFtempname, Note: mkstemp, *note tmpfile:
     XREFtmpfile.

 -- : P_tmpdir ()
     Return the name of the host system’s *default* directory for
     temporary files.

     Programming Note: The value returned by ‘P_tmpdir’ is always the
     default location.  This value may not agree with that returned from
     ‘tempdir’ if the user has overridden the default with the ‘TMPDIR’
     environment variable.

     See also: Note: tempdir, Note: tempname,
     Note: mkstemp, Note: tmpfile.