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

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  tem-
       plate,  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  re-
       placed  with a string that makes	the filename unique.  Since it will be
       modified, template must not be a	string constant,  but  should  be  de-
       clared 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 the
       following  bits--with the same meaning as for open(2)--may be specified
       in flags: O_APPEND, O_CLOEXEC, and O_SYNC.  Note	that when creating the
       file, mkostemp()	includes the values O_RDWR, O_CREAT, and O_EXCL	in the
       flags argument given to open(2);	including these	values	in  the	 flags
       argument	 given	to  mkostemp()	is unnecessary,	and produces errors on
       some systems.

       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 mk-
       stemp().

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  tem-
	      plate were not XXXXXX; now template is unchanged.

	      For  mkstemps() and mkostemps(): template	is less	than (6	+ suf-
	      fixlen) 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.

ATTRIBUTES
   Multithreading (see pthreads(7))
       The  mkstemp(),	mkostemp(),  mkstemps(), and mkostemps() functions are
       thread-safe.

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  permis-
       sions  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 any-
       thing 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()).

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

COLOPHON
       This page is part of release 3.74 of the	Linux  man-pages  project.   A
       description  of	the project, information about reporting bugs, and the
       latest	 version    of	  this	  page,	   can	   be	  found	    at
       http://www.kernel.org/doc/man-pages/.

GNU				  2014-08-19			    MKSTEMP(3)

NAME | SYNOPSIS | DESCRIPTION | RETURN VALUE | ERRORS | VERSIONS | ATTRIBUTES | CONFORMING TO | NOTES | SEE ALSO | COLOPHON

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