1tmpnam(3C) Standard C Library Functions tmpnam(3C)
2
6 tmpnam, tmpnam_r, tempnam - create a name for a temporary file
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9 #include <stdio.h>
10 char *tmpnam(char *s);
12 char *tmpnam_r(char *s);
15 char *tempnam(const char *dir, const char *pfx);
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21 These functions generate file names that can be used safely for a tem‐
22 porary file.
23 tmpnam()
25 The tmpnam() function always generates a file name using the path pre‐
26 fix defined as P_tmpdir in the <stdio.h> header. On Solaris systems,
27 the default value for P_tmpdir is /var/tmp. If s is NULL, tmpnam()
28 leaves its result in a thread-specific data area and returns a pointer
29 to that area. The next call to tmpnam() by the same thread will destroy
30 the contents of the area. If s is not NULL, it is assumed to be the
31 address of an array of at least L_tmpnam bytes, where L_tmpnam is a
32 constant defined through inclusion of <stdio.h>. The tmpnam() function
33 places its result in that array and returns s.
34 tmpnam_r()
36 The tmpnam_r() function has the same functionality as tmpnam() except
37 that if s is a null pointer, the function returns NULL.
38 tempnam()
40 The tempnam() function allows the user to control the choice of a
41 directory. The argument dir points to the name of the directory in
42 which the file is to be created. If dir is NULL or points to a string
43 that is not a name for an appropriate directory, the path prefix
44 defined as P_tmpdir in the <stdio.h> header is used. If that directory
45 is not accessible, /tmp is used. If, however, the TMPDIR environment
46 variable is set in the user's environment, its value is used as the
47 temporary-file directory.
48 Many applications prefer that temporary files have certain initial
51 character sequences in their names. The pfx argument may be NULL or
52 point to a string of up to five characters to be used as the initial
53 characters of the temporary-file name.
54 Upon successful completion, tempnam() uses malloc(3C) to allocate space
57 for a string, puts the generated pathname in that space, and returns a
58 pointer to it. The pointer is suitable for use in a subsequent call to
59 free(). If tempnam() cannot return the expected result for any reason
60 (for example, malloc() failed), or if none of the above-mentioned
61 attempts to find an appropriate directory was successful, a null
62 pointer is returned and errno is set to indicate the error.
63
65 The tempnam() function will fail if:
66 ENOMEM Insufficient storage space is available.
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71 These functions generate a different file name each time they are
72 called.
73 Files created using these functions and either fopen(3C) or creat(2)
76 are temporary only in the sense that they reside in a directory
77 intended for temporary use, and their names are unique. It is the
78 user's responsibility to remove the file when its use is ended.
79 If called more than TMP_MAX (defined in <stdio.h>) times in a single
82 process, these functions start recycling previously used names.
83 Between the time a file name is created and the file is opened, it is
86 possible for some other process to create a file with the same name.
87 This can never happen if that other process is using these functions or
88 mktemp(3C) and the file names are chosen to render duplication by other
89 means unlikely.
90 The tmpnam() function is safe to use in multithreaded applications
93 because it employs thread-specific data if it is passed a NULL pointer.
94 However, its use is discouraged. The tempnam() function is safe in mul‐
95 tithreaded applications and should be used instead.
96 When compiling multithreaded applications, the _REENTRANT flag must be
99 defined on the compile line. This flag should be used only with multi‐
100 threaded applications.
101
103 See attributes(5) for descriptions of the following attributes:
104 ┌─────────────────────────────┬─────────────────────────────────────┐
109 │ ATTRIBUTE TYPE │ ATTRIBUTE VALUE │
110 ├─────────────────────────────┼─────────────────────────────────────┤
111 │Interface Stability │tmpnam() and tempnam() are Standard. │
112 ├─────────────────────────────┼─────────────────────────────────────┤
113 │MT-Level │Safe │
114 └─────────────────────────────┴─────────────────────────────────────┘
115
117 creat(2), unlink(2), fopen(3C), free(3C), malloc(3C), mktemp(3C),
118 mkstemp(3C), tmpfile(3C), attributes(5), standards(5)
119SunOS 5.11 18 May 2004 tmpnam(3C)