tempnam(3p) [centos man page]

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

       tempnam - create a name for a temporary file

SYNOPSIS

       #include <stdio.h>

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

DESCRIPTION

       The tempnam() function shall generate a pathname that may be used for a temporary file.

       The tempnam() function allows the user to control the choice of a directory. The dir argument points to the name of the directory in  which
       the file is to be created. If dir is a null pointer or points to a string which is not a name for an appropriate directory, the path prefix
       defined as P_tmpdir in the <stdio.h> header shall be used. If that directory is not accessible, an implementation-defined directory may	be
       used.

       Many applications prefer their temporary files to have certain initial letter sequences in their names. The pfx argument should be used for
       this. This argument may be a null pointer or point to a string of up to five bytes to be used as the beginning of the filename.

       Some implementations of tempnam() may use tmpnam() internally.  On such implementations, if called more than {TMP_MAX} times  in  a  single
       process, the behavior is implementation-defined.

RETURN VALUE

       Upon  successful completion, tempnam() shall allocate space for a string, put the generated pathname in that space, and return a pointer to
       it. The pointer shall be suitable for use in a subsequent call to free(). Otherwise, it shall return a null pointer and set errno to  indi-
       cate the error.

ERRORS

       The tempnam() function shall fail if:

       ENOMEM Insufficient storage space is available.

       The following sections are informative.

EXAMPLES

   Generating a Pathname
       The  following  example generates a pathname for a temporary file in directory /tmp, with the prefix file. After the filename has been cre-
       ated, the call to free() deallocates the space used to store the filename.

	      #include <stdio.h>
	      #include <stdlib.h>
	      ...
	      char *directory = "/tmp";
	      char *fileprefix = "file";
	      char *file;

	      file = tempnam(directory, fileprefix);
	      free(file);

APPLICATION USAGE

       This function only creates pathnames. 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(), free(), open(), tmpfile(), tmpnam(), 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							       TEMPNAM(3P)

Check Out this Related Man Page

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

       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 appropriate.

       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

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

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
       mkstemp(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.

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

SEE ALSO

       mkstemp(3), mktemp(3), tmpfile(3), tmpnam(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/.

								    2008-08-06								TEMPNAM(3)

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tempnam(3p) [centos man page]

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