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/.