mirror of https://github.com/mkerrisk/man-pages
93 lines
3.2 KiB
Groff
93 lines
3.2 KiB
Groff
.\" Copyright 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.\" manual page may be incorrect or out-of-date.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 18:48:48 1993 by Rik Faith (faith@cs.unc.edu)
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.\" Modified 980310, aeb
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.\" Modified 990328, aeb
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.\"
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.TH MKSTEMP 3 2001-12-23 "GNU" "Linux Programmer's Manual"
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.SH NAME
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mkstemp \- create a unique temporary file
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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 "int mkstemp(char *" template );
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.fi
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.SH DESCRIPTION
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The \fBmkstemp\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. The file is then created with mode read/write and
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permissions 0666 (glibc 2.0.6 and earlier), 0600 (glibc 2.0.7 and later).
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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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The file is opened with the
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.BR open (2)
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.B O_EXCL
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flag, guaranteeing that when
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.BR mkstemp ()
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returns successfully we are the only user.
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.SH "RETURN VALUE"
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On success, the \fBmkstemp\fP() function returns the file descriptor
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of the temporary file.
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On error, \-1 is returned, and
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.I errno
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is set appropriately.
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.SH ERRORS
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.TP
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.B EEXIST
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Could not create a unique temporary filename.
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Now the contents of \fItemplate\fP are undefined.
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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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Now \fItemplate\fP is unchanged.
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.SH NOTES
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The old behaviour (creating a file with mode 0666) may be
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a security risk, especially since other Unix flavours use 0600,
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and somebody might overlook this detail when porting programs.
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More generally, the POSIX specification does not say anything
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about file modes, so the application should make sure its umask
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is set appropriately before calling
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.BR mkstemp ().
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.SH "CONFORMING TO"
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4.3BSD, POSIX 1003.1-2001
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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 "SEE ALSO"
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.BR mkdtemp (3),
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.BR mktemp (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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