1TMPNAM(3P) POSIX Programmer's Manual TMPNAM(3P)
2
6 This manual page is part of the POSIX Programmer's Manual. The Linux
7 implementation of this interface may differ (consult the corresponding
8 Linux manual page for details of Linux behavior), or the interface may
9 not be implemented on Linux.
10
12 tmpnam — create a name for a temporary file
13
15 #include <stdio.h>
16 char *tmpnam(char *s);
18
20 The functionality described on this reference page is aligned with the
21 ISO C standard. Any conflict between the requirements described here
22 and the ISO C standard is unintentional. This volume of POSIX.1‐2017
23 defers to the ISO C standard.
24 The tmpnam() function shall generate a string that is a valid pathname
26 that does not name an existing file. The function is potentially capa‐
27 ble of generating {TMP_MAX} different strings, but any or all of them
28 may already be in use by existing files and thus not be suitable return
29 values.
30 The tmpnam() function generates a different string each time it is
32 called from the same process, up to {TMP_MAX} times. If it is called
33 more than {TMP_MAX} times, the behavior is implementation-defined.
34 The implementation shall behave as if no function defined in this vol‐
36 ume of POSIX.1‐2017, except tempnam(), calls tmpnam().
37 The tmpnam() function need not be thread-safe if called with a NULL
39 parameter.
40
42 Upon successful completion, tmpnam() shall return a pointer to a
43 string. If no suitable string can be generated, the tmpnam() function
44 shall return a null pointer.
45 If the argument s is a null pointer, tmpnam() shall leave its result in
47 an internal static object and return a pointer to that object. Subse‐
48 quent calls to tmpnam() may modify the same object. If the argument s
49 is not a null pointer, it is presumed to point to an array of at least
50 L_tmpnam chars; tmpnam() shall write its result in that array and shall
51 return the argument as its value.
52
54 No errors are defined.
55 The following sections are informative.
57
59 Generating a Pathname
60 The following example generates a unique pathname and stores it in the
61 array pointed to by ptr.
62 #include <stdio.h>
65 ...
66 char pathname[L_tmpnam+1];
67 char *ptr;
68 ptr = tmpnam(pathname);
70
72 This function only creates pathnames. It is the application's responsi‐
73 bility to create and remove the files.
74 Between the time a pathname is created and the file is opened, it is
76 possible for some other process to create a file with the same name.
77 Applications may find tmpfile() more useful.
78 Applications should use the tmpfile(), mkstemp(), or mkdtemp() func‐
80 tions instead of the obsolescent tmpnam() function.
81
83 None.
84
86 The tmpnam() function may be removed in a future version.
87
89 fopen(), open(), mkdtemp(), tempnam(), tmpfile(), unlink()
90 The Base Definitions volume of POSIX.1‐2017, <stdio.h>
92
94 Portions of this text are reprinted and reproduced in electronic form
95 from IEEE Std 1003.1-2017, Standard for Information Technology -- Por‐
96 table Operating System Interface (POSIX), The Open Group Base Specifi‐
97 cations Issue 7, 2018 Edition, Copyright (C) 2018 by the Institute of
98 Electrical and Electronics Engineers, Inc and The Open Group. In the
99 event of any discrepancy between this version and the original IEEE and
100 The Open Group Standard, the original IEEE and The Open Group Standard
101 is the referee document. The original Standard can be obtained online
102 at http://www.opengroup.org/unix/online.html .
103 Any typographical or formatting errors that appear in this page are
105 most likely to have been introduced during the conversion of the source
106 files to man page format. To report such errors, see https://www.ker‐
107 nel.org/doc/man-pages/reporting_bugs.html .
108IEEE/The Open Group 2017 TMPNAM(3P)