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

NAME
       tempnam - create	a name for a temporary file

SYNOPSIS
       #include	<stdio.h>

       char *tempnam(const char	*dir, const char *pfx);

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

       tempnam(): _BSD_SOURCE || _SVID_SOURCE

DESCRIPTION
       Never use this function.	 Use mkstemp(3)	or tmpfile(3) instead.

       The  tempnam()  function	 returns a pointer to a	string that is a valid
       filename, and such that a file with this	name did not exist when	 temp-
       nam()  checked.	 The  filename	suffix	of the pathname	generated will
       start with pfx in case pfx is a non-NULL	string of at most five	bytes.
       The  directory  prefix part of the pathname generated is	required to be
       "appropriate" (often that at least implies writable).

       Attempts	to find	an appropriate	directory  go  through	the  following
       steps:

       a) In case the environment variable TMPDIR exists and contains the name
	  of an	appropriate directory, that is used.

       b) Otherwise, if	the dir	argument is non-NULL and  appropriate,	it  is
	  used.

       c) Otherwise, P_tmpdir (as defined in _stdio.h_)	is used	when appropri-
	  ate.

       d) Finally an implementation-defined directory may be used.

       The string returned by tempnam()	is allocated using malloc(3) and hence
       should be freed by free(3).

RETURN VALUE
       On success, the tempnam() function returns a pointer to a unique	tempo-
       rary filename.  It returns NULL if a unique name	cannot	be  generated,
       with errno set to indicate the cause of the error.

ERRORS
       ENOMEM Allocation of storage failed.

CONFORMING TO
       SVr4, 4.3BSD, POSIX.1-2001.  POSIX.1-2008 marks tempnam() as obsolete.

NOTES
       Although	 tempnam()  generates names that are difficult to guess, it is
       nevertheless possible that between the time that	 tempnam()  returns  a
       pathname, and the time that the program opens it, another program might
       create that pathname using open(2), or create it	as  a  symbolic	 link.
       This  can lead to security holes.  To avoid such	possibilities, use the
       open(2) O_EXCL flag to open the	pathname.   Or	better	yet,  use  mk-
       stemp(3)	or tmpfile(3).

       SUSv2  does  not	mention	the use	of TMPDIR; glibc will use it only when
       the program is not set-user-ID.	On SVr4, the directory used  under  d)
       is /tmp (and this is what glibc does).

       Because	it  dynamically	 allocates memory used to return the pathname,
       tempnam() is reentrant, and thus	thread safe, unlike tmpnam(3).

       The tempnam() function generates	a different string  each  time	it  is
       called,	up  to	TMP_MAX	(defined in _stdio.h_) times.  If it is	called
       more than TMP_MAX times,	the behavior is	implementation defined.

       tempnam() uses at most the first	five bytes from	pfx.

       The glibc implementation	of tempnam() will fail with the	 error	EEXIST
       upon failure to find a unique name.

BUGS
       The  precise  meaning  of "appropriate" is undefined; it	is unspecified
       how accessibility of a directory	is determined.

SEE ALSO
       mkstemp(3), mktemp(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/.

				  2014-02-27			    TEMPNAM(3)

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

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