mkstemp(3) [bsd man page]

MKTEMP(3)						     Library Functions Manual							 MKTEMP(3)

NAME

       mktemp - make a unique file name

SYNOPSIS

       char *mktemp(template)
       char *template;

       mkstemp(template)
       char *template;

DESCRIPTION

       Mktemp creates a unique file name and returns the address of the template.  The template should contain a file name with trailing X's, nor-
       mally something like /tmp/tempXXXXXX.  The X's are replaced by the current process number and/or  a  unique  letter  combination.   Mkstemp
       makes the same replacement to the template but opens the template file and returns a file descriptor open for reading and writing.  Mkstemp
       avoids the race between testing whether the file exists and opening it for use.	The number of file name combinations  mktemp  and  mkstemp
       will try depends on the number of X's placed on the end of the template; six X's will result in them trying roughly 26 ** 6 combinations.

SEE ALSO

       access(2), getpid(2), open(2)

DIAGNOSTICS

       Mktemp returns NULL on failure, mkstemp returns -1 if no suitable file could be created.

7th Edition							  April 10, 1987							 MKTEMP(3)

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

NAME

       mktemp - make a unique temporary filename

SYNOPSIS

       #include <stdlib.h>

       char *mktemp(char *template);

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

       mktemp():
	      Since glibc 2.12:
		  _BSD_SOURCE || _SVID_SOURCE ||
		      (_XOPEN_SOURCE >= 500 ||
			   _XOPEN_SOURCE && _XOPEN_SOURCE_EXTENDED) &&
		      !(_POSIX_C_SOURCE >= 200112L || _XOPEN_SOURCE >= 600)
	      Before glibc 2.12:
		  _BSD_SOURCE || _SVID_SOURCE || _XOPEN_SOURCE >= 500 || _XOPEN_SOURCE && _XOPEN_SOURCE_EXTENDED

DESCRIPTION

       The  mktemp()  function	generates a unique temporary filename from template.  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.

RETURN VALUE

       The  mktemp()  function	always	returns template.  If a unique name was created, the last six bytes of template will have been modified in
       such a way that the resulting name is unique (i.e., does not exist already) If a unique name could not be  created,  template  is  made	an
       empty string.

ERRORS

       EINVAL The last six characters of template were not XXXXXX.

CONFORMING TO

       4.3BSD, POSIX.1-2001.  POSIX.1-2008 removes the specification of mktemp().

NOTES

       The prototype is in <unistd.h> for libc4, libc5, glibc1; glibc2 follows the Single Unix Specification and has the prototype in <stdlib.h>.

BUGS

       Never  use  mktemp().  Some implementations follow 4.3BSD and replace XXXXXX by the current process ID and a single letter, so that at most
       26 different names can be returned.  Since on the one hand the names are easy to guess, and on the other hand there is a race between test-
       ing whether the name exists and opening the file, every use of mktemp() is a security risk.  The race is avoided by mkstemp(3).

SEE ALSO

       mkstemp(3), tempnam(3), tmpfile(3), tmpnam(3)

COLOPHON

       This  page is part of release 3.27 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
								    2010-09-20								 MKTEMP(3)