MKSTEMP(3)                                          Linux Programmer's Manual                                         MKSTEMP(3)



NAME
       mkstemp, mkostemp - create a unique temporary file

SYNOPSIS
       #include <stdlib.h>

       int mkstemp(char *template);

       int mkostemp (char *template, int flags);

       int mkstemps(char *template, int suffixlen);

       int mkostemps(char *template, int suffixlen, int flags);

   Feature Test Macro Requirements for glibc (see feature_test_macros(7)):

       mkstemp(): _BSD_SOURCE || _SVID_SOURCE || _XOPEN_SOURCE >= 500
       mkostemp(): _GNU_SOURCE
       mkstemps(): _BSD_SOURCE || _SVID_SOURCE
       mkostemps(): _GNU_SOURCE

DESCRIPTION
       The  mkstemp()  function  generates a unique temporary filename from template, creates and opens the file, and returns an
       open file descriptor for the file.

       The last six characters of template must be "XXXXXX" and these are replaced with a string that makes the filename unique.
       Since it will be modified, template must not be a string constant, but should be declared as a character array.

       The file is created with permissions 0600, that is, read plus write for owner only.  (In glibc versions 2.06 and earlier,
       the file is created with permissions 0666, that is, read and write for all users.)  The returned file descriptor provides
       both read and write access to the file.  The file is opened with the open(2) O_EXCL flag, guaranteeing that the caller is
       the process that creates the file.

       The mkostemp() function is like mkstemp(), with the difference that flags as for open(2) may be specified in flags (e.g.,
       O_APPEND, O_SYNC).

       The  mkstemps() function is like mkstemp(), except that the string in template contains a suffix of suffixlen characters.
       Thus, template is of the form prefixXXXXXXsuffix, and the string XXXXXX is modified as for mkstemp().

       The mkostemps() function is to mkstemps() as mkostemp() is to mkstemp().

RETURN VALUE
       On success, these functions return the file descriptor of the temporary file.  On error, -1 is returned, and errno is set
       appropriately.

ERRORS
       EEXIST Could not create a unique temporary filename.  Now the contents of template are undefined.

       EINVAL For mkstemp() and mkostemp(): The last six characters of template were not XXXXXX; now template is unchanged.

              For  mkstemps()  and  mkostemps()  template is less than (6 + suffixlen) characters long, or the last 6 characters
              before the suffix in template were not XXXXXX.

       These functions may also fail with any of the errors described for open(2).

VERSIONS
       mkostemp() is available since glibc 2.7.  mkstemps() and mkostemps() are available since glibc 2.11.

CONFORMING TO
       mkstemp(): 4.3BSD, POSIX.1-2001.

       mkstemps(): unstandardized, but appears on several other systems.

       mkostemp() and mkostemps(): are glibc extensions.

NOTES
       The old behavior of creating a file with mode 0666 may be a security risk, especially since other Unix flavors use  0600,
       and somebody might overlook this detail when porting programs.

       More  generally,  the  POSIX specification of mkstemp() does not say anything about file modes, so the application should
       make sure its file mode creation mask (see umask(2)) is set appropriately before calling mkstemp() (and mkostemp()).

       The prototype for mktemp() is in <unistd.h> for libc4, libc5, glibc1; glibc2 follows POSIX.1 and  has  the  prototype  in
       <stdlib.h>.

SEE ALSO
       mkdtemp(3), mktemp(3), tempnam(3), tmpfile(3), tmpnam(3)

COLOPHON
       This  page  is  part of release 3.25 of the Linux man-pages project.  A description of the project, and information about
       reporting bugs, can be found at http://www.kernel.org/doc/man-pages/.



GNU                                                        2010-06-19                                                 MKSTEMP(3)