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NAME

       mkstemp, mkostemp - create a unique temporary file

SYNOPSIS

       #include <stdlib.h>

       int mkstemp(char *template);

       int mkostemp (char *template, int flags);

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

       mkstemp(): _BSD_SOURCE || _SVID_SOURCE || _XOPEN_SOURCE >= 500
       mkostemp(): _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.

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

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 The last six  characters  of  template  were  not  XXXXXX.   Now
              template is unchanged.

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

VERSIONS

       mkostemp() is available since glibc 2.7.

CONFORMING TO

       mkstemp(): 4.3BSD, POSIX.1-2001.  mkostemp(): is a glibc extension.

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

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