| .\" Copyright (C) 1993 David Metcalfe (david@prism.demon.co.uk) |
| .\" |
| .\" %%%LICENSE_START(VERBATIM) |
| .\" Permission is granted to make and distribute verbatim copies of this |
| .\" manual provided the copyright notice and this permission notice are |
| .\" preserved on all copies. |
| .\" |
| .\" Permission is granted to copy and distribute modified versions of this |
| .\" manual under the conditions for verbatim copying, provided that the |
| .\" entire resulting derived work is distributed under the terms of a |
| .\" permission notice identical to this one. |
| .\" |
| .\" Since the Linux kernel and libraries are constantly changing, this |
| .\" manual page may be incorrect or out-of-date. The author(s) assume no |
| .\" responsibility for errors or omissions, or for damages resulting from |
| .\" the use of the information contained herein. The author(s) may not |
| .\" have taken the same level of care in the production of this manual, |
| .\" which is licensed free of charge, as they might when working |
| .\" professionally. |
| .\" |
| .\" Formatted or processed versions of this manual, if unaccompanied by |
| .\" the source, must acknowledge the copyright and authors of this work. |
| .\" %%%LICENSE_END |
| .\" |
| .\" References consulted: |
| .\" Linux libc source code |
| .\" Lewine's _POSIX Programmer's Guide_ (O'Reilly & Associates, 1991) |
| .\" 386BSD man pages |
| .\" Modified Sat Jul 24 18:48:06 1993 by Rik Faith (faith@cs.unc.edu) |
| .\" Modified Fri Jun 23 01:26:34 1995 by Andries Brouwer (aeb@cwi.nl) |
| .\" (prompted by Scott Burkett <scottb@IntNet.net>) |
| .\" Modified Sun Mar 28 23:44:38 1999 by Andries Brouwer (aeb@cwi.nl) |
| .\" |
| .TH MKTEMP 3 2017-09-15 "GNU" "Linux Programmer's Manual" |
| .SH NAME |
| mktemp \- make a unique temporary filename |
| .SH SYNOPSIS |
| .nf |
| .B #include <stdlib.h> |
| .PP |
| .BI "char *mktemp(char *" template ); |
| .fi |
| .PP |
| .in -4n |
| Feature Test Macro Requirements for glibc (see |
| .BR feature_test_macros (7)): |
| .in |
| .PP |
| .BR mktemp (): |
| .ad l |
| .PD 0 |
| .RS 4 |
| .TP 4 |
| Since glibc 2.12: |
| (_XOPEN_SOURCE\ >=\ 500) && ! (_POSIX_C_SOURCE\ >=\ 200112L) |
| || /* Glibc since 2.19: */ _DEFAULT_SOURCE |
| || /* Glibc <= 2.19: */ _SVID_SOURCE || _BSD_SOURCE |
| .TP |
| Before glibc 2.12: |
| _BSD_SOURCE || _SVID_SOURCE || _XOPEN_SOURCE\ >=\ 500 |
| .\" || _XOPEN_SOURCE\ &&\ _XOPEN_SOURCE_EXTENDED |
| .RE |
| .PD |
| .ad b |
| .SH DESCRIPTION |
| .IR "Never use this function" ; |
| see BUGS. |
| .PP |
| The |
| .BR mktemp () |
| function generates a unique temporary filename |
| from \fItemplate\fP. |
| The last six characters of \fItemplate\fP must |
| be XXXXXX and these are replaced with a string that makes the |
| filename unique. |
| Since it will be modified, |
| .I template |
| must not be a string constant, but should be declared as a character array. |
| .SH RETURN VALUE |
| The |
| .BR mktemp () |
| function always returns \fItemplate\fP. |
| If a unique name was created, the last six bytes of \fItemplate\fP 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, |
| \fItemplate\fP is made an empty string, and |
| .I errno |
| is set to indicate the error. |
| .SH ERRORS |
| .TP |
| .B EINVAL |
| The last six characters of \fItemplate\fP were not XXXXXX. |
| .SH ATTRIBUTES |
| For an explanation of the terms used in this section, see |
| .BR attributes (7). |
| .TS |
| allbox; |
| lb lb lb |
| l l l. |
| Interface Attribute Value |
| T{ |
| .BR mktemp () |
| T} Thread safety MT-Safe |
| .TE |
| .SH CONFORMING TO |
| 4.3BSD, POSIX.1-2001. |
| POSIX.1-2008 removes the specification of |
| .BR mktemp (). |
| .\" .SH NOTES |
| .\" The prototype is in |
| .\" .I <unistd.h> |
| .\" for libc4, libc5, glibc1; glibc2 follows the Single UNIX Specification |
| .\" and has the prototype in |
| .\" .IR <stdlib.h> . |
| .SH BUGS |
| Never use |
| .BR 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 testing whether the name exists and |
| opening the file, every use of |
| .BR mktemp () |
| is a security risk. |
| The race is avoided by |
| .BR mkstemp (3) |
| and |
| .BR mkdtemp (3). |
| .SH SEE ALSO |
| .BR mktemp (1), |
| .BR mkdtemp (3), |
| .BR mkstemp (3), |
| .BR tempnam (3), |
| .BR tmpfile (3), |
| .BR tmpnam (3) |
