NAME

       mkstemp, mkostemp, mkstemps, mkostemps - 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 ||
           _XOPEN_SOURCE && _XOPEN_SOURCE_EXTENDED
           || /* Since glibc 2.12: */ _POSIX_C_SOURCE >= 200112L

       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.  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

       In glibc versions 2.06 and earlier, the file is created with permissions  0666,  that  is,
       read  and write for all users.  This old behavior may be a security risk, especially since
       other UNIX flavors use  0600,  and  somebody  might  overlook  this  detail  when  porting
       programs.  POSIX.1-2008 adds a requirement that the file be created with mode 0600.

       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 3.54 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/.