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mktemp(3) [bsd man page]

MKTEMP(3)						     Library Functions Manual							 MKTEMP(3)

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)

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

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 3.44 of the Linux man-pages project. A description of the project, and information about reporting bugs, can be found at GNU
2010-09-20 MKTEMP(3)
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