mirror of https://github.com/mkerrisk/man-pages
81 lines
3.2 KiB
Groff
81 lines
3.2 KiB
Groff
.\" Copyright (C) 1993 David Metcalfe (david@prism.demon.co.uk)
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.\"
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.\" Permission is granted to make and distribute verbatim copies of this
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.\" manual provided the copyright notice and this permission notice are
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.\" preserved on all copies.
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.\"
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.\" Permission is granted to copy and distribute modified versions of this
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.\" manual under the conditions for verbatim copying, provided that the
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.\" entire resulting derived work is distributed under the terms of a
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.\" permission notice identical to this one.
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.\"
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.\" Since the Linux kernel and libraries are constantly changing, this
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.\" manual page may be incorrect or out-of-date. The author(s) assume no
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.\" responsibility for errors or omissions, or for damages resulting from
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.\" the use of the information contained herein. The author(s) may not
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.\" have taken the same level of care in the production of this manual,
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.\" which is licensed free of charge, as they might when working
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.\" professionally.
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.\"
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.\" Formatted or processed versions of this manual, if unaccompanied by
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.\" the source, must acknowledge the copyright and authors of this work.
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.\"
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.\" References consulted:
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.\" Linux libc source code
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.\" Lewine's _POSIX Programmer's Guide_ (O'Reilly & Associates, 1991)
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.\" 386BSD man pages
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.\" Modified Sat Jul 24 18:48:06 1993 by Rik Faith (faith@cs.unc.edu)
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.\" Modified Fri Jun 23 01:26:34 1995 by Andries Brouwer (aeb@cwi.nl)
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.\" (prompted by Scott Burkett <scottb@IntNet.net>)
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.\" Modified Sun Mar 28 23:44:38 1999 by Andries Brouwer (aeb@cwi.nl)
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.\"
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.TH MKTEMP 3 1993-04-03 "GNU" "Linux Programmer's Manual"
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.SH NAME
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mktemp \- make a unique temporary filename
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.SH SYNOPSIS
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.nf
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.B #include <stdlib.h>
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.sp
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.BI "char *mktemp(char *" template );
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.fi
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.SH DESCRIPTION
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The \fBmktemp\fP() function generates a unique temporary filename
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from \fItemplate\fP. The last six characters of \fItemplate\fP must
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be XXXXXX and these are replaced with a string that makes the
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filename unique. Since it will be modified,
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.I template
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must not be a string constant, but should be declared as a character array.
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.SH "RETURN VALUE"
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The \fBmktemp\fP() function returns NULL on error (\fItemplate\fP did not
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end in XXXXXX) and \fItemplate\fP otherwise.
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If the call was successful, the last six bytes of \fItemplate\fP will
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have been modified in such a way that the resulting name is unique
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(does not exist already). If the call was unsuccessful, \fItemplate\fP
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is made an empty string.
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.SH ERRORS
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.TP
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.B EINVAL
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The last six characters of \fItemplate\fP were not XXXXXX.
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.SH "CONFORMING TO"
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4.3BSD, POSIX.1-2001.
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.SH NOTE
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The prototype is in
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.I <unistd.h>
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for libc4, libc5, glibc1; glibc2 follows the Single Unix Specification
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and has the prototype in
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.IR <stdlib.h> .
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.SH BUGS
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Never use \fBmktemp\fP(). Some implementations follow 4.3BSD
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and replace XXXXXX by the current process ID and a single letter,
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so that at most 26 different names can be returned.
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Since on the one hand the names are easy to guess, and on the other
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hand there is a race between testing whether the name exists and
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opening the file, every use of \fBmktemp\fP() is a security risk.
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The race is avoided by
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.BR mkstemp (3).
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.SH "SEE ALSO"
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.BR mkstemp (3),
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.BR tempnam (3),
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.BR tmpfile (3),
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.BR tmpnam (3)
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