tmpnam(3p) [centos man page]

TMPNAM(3P)						     POSIX Programmer's Manual							TMPNAM(3P)

PROLOG

       This  manual page is part of the POSIX Programmer's Manual.  The Linux implementation of this interface may differ (consult the correspond-
       ing Linux manual page for details of Linux behavior), or the interface may not be implemented on Linux.

NAME

       tmpnam - create a name for a temporary file

SYNOPSIS

       #include <stdio.h>

       char *tmpnam(char *s);

DESCRIPTION

       The tmpnam() function shall generate a string that is a valid filename and that is not the same as the name of an existing file. The  func-
       tion  is  potentially capable of generating {TMP_MAX} different strings, but any or all of them may already be in use by existing files and
       thus not be suitable return values.

       The tmpnam() function generates a different string each time it is called from the same process, up to {TMP_MAX} times.	If  it	is  called
       more than {TMP_MAX} times, the behavior is implementation-defined.

       The implementation shall behave as if no function defined in this volume of IEEE Std 1003.1-2001 calls tmpnam().

       If  the	application  uses  any	of  the  functions  guaranteed to be available if either _POSIX_THREAD_SAFE_FUNCTIONS or _POSIX_THREADS is
       defined, the application shall ensure that the tmpnam() function is called with a non-NULL parameter.

RETURN VALUE

       Upon successful completion, tmpnam() shall return a pointer to a string. If no suitable string can  be  generated,  the	tmpnam()  function
       shall return a null pointer.

       If the argument s is a null pointer, tmpnam() shall leave its result in an internal static object and return a pointer to that object. Sub-
       sequent calls to tmpnam() may modify the same object. If the argument s is not a null pointer, it is presumed to point to an  array  of	at
       least L_tmpnam chars; tmpnam() shall write its result in that array and shall return the argument as its value.

ERRORS

       No errors are defined.

       The following sections are informative.

EXAMPLES

   Generating a Filename
       The following example generates a unique filename and stores it in the array pointed to by ptr.

	      #include <stdio.h>
	      ...
	      char filename[L_tmpnam+1];
	      char *ptr;

	      ptr = tmpnam(filename);

APPLICATION USAGE

       This function only creates filenames. It is the application's responsibility to create and remove the files.

       Between	the  time a pathname is created and the file is opened, it is possible for some other process to create a file with the same name.
       Applications may find tmpfile() more useful.

RATIONALE

       None.

FUTURE DIRECTIONS

       None.

SEE ALSO

       fopen(), open(), tempnam(), tmpfile(), unlink(), the Base Definitions volume of IEEE Std 1003.1-2001, <stdio.h>

COPYRIGHT

       Portions of this text are reprinted and reproduced in electronic form from IEEE Std 1003.1, 2003 Edition, Standard for Information Technol-
       ogy -- Portable Operating System Interface (POSIX), The Open Group Base Specifications Issue 6, Copyright (C) 2001-2003 by the Institute of
       Electrical and Electronics Engineers, Inc and The Open Group. In the event of any discrepancy between this version and  the  original  IEEE
       and  The  Open Group Standard, the original IEEE and The Open Group Standard is the referee document. The original Standard can be obtained
       online at http://www.opengroup.org/unix/online.html .

IEEE
/The Open Group						       2003								TMPNAM(3P)

Check Out this Related Man Page

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

NAME

       tmpnam, tmpnam_r - create a name for a temporary file

SYNOPSIS

       #include <stdio.h>

       char *tmpnam(char *s);

DESCRIPTION

       The  tmpnam()  function	returns  a pointer to a string that is a valid filename, and such that a file with this name did not exist at some
       point in time, so that naive programmers may think it a suitable name for a temporary file.  If the argument s is NULL this name is  gener-
       ated in an internal static buffer and may be overwritten by the next call to tmpnam().  If s is not NULL, the name is copied to the charac-
       ter array (of length at least L_tmpnam) pointed to by s and the value s is returned in case of success.

       The pathname that is created, has a directory prefix P_tmpdir.  (Both L_tmpnam and P_tmpdir are defined in <stdio.h>, just like the TMP_MAX
       mentioned below.)

RETURN VALUE

       The tmpnam() function returns a pointer to a unique temporary filename, or NULL if a unique name cannot be generated.

ERRORS

       No errors are defined.

CONFORMING TO

       SVr4, 4.3BSD, C89, C99, POSIX.1-2001.  POSIX.1-2008 marks tmpnam() as obsolete.

NOTES

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

       Although tmpnam() generates names that are difficult to guess, it is nevertheless possible that between the time that  tmpnam()	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
       mkstemp(3) or tmpfile(3).

       Portable  applications  that use threads cannot call tmpnam() with a NULL argument if either _POSIX_THREADS or _POSIX_THREAD_SAFE_FUNCTIONS
       is defined.

       A POSIX draft proposed to use a function tmpnam_r() defined by

	   char *
	   tmpnam_r(char *s)
	   {
	       return s ? tmpnam(s) : NULL;
	   }

       apparently as a warning not to use NULL.  A few systems implement it.  To get a glibc prototype for this function  from	<stdio.h>,  define
       _SVID_SOURCE or _BSD_SOURCE (before including any header file).

BUGS

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

SEE ALSO

       mkstemp(3), mktemp(3), tempnam(3), tmpfile(3)

COLOPHON

       This  page is part of release 3.44 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/.

								    2010-09-10								 TMPNAM(3)

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tmpnam(3p) [centos man page]

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