1MKSTEMP(3) Linux Programmer's Manual MKSTEMP(3)
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6 mkstemp - create a unique temporary file
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9 #include <stdlib.h>
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11 int mkstemp(char *template);
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14 The mkstemp() function generates a unique temporary filename from tem‐
15 plate. The last six characters of template must be XXXXXX and these
16 are replaced with a string that makes the filename unique. The file is
17 then created with mode read/write and permissions 0666 (glibc 2.0.6 and
18 earlier), 0600 (glibc 2.0.7 and later). Since it will be modified,
19 template must not be a string constant, but should be declared as a
20 character array. The file is opened with the open(2) O_EXCL flag,
21 guaranteeing that when mkstemp() returns successfully we are the only
22 user.
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25 On success, the mkstemp() function returns the file descriptor of the
26 temporary file. On error, -1 is returned, and errno is set appropri‐
27 ately.
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30 EEXIST Could not create a unique temporary filename. Now the contents
31 of template are undefined.
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33 EINVAL The last six characters of template were not XXXXXX. Now tem‐
34 plate is unchanged.
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37 The old behaviour (creating a file with mode 0666) may be a security
38 risk, especially since other Unix flavours use 0600, and somebody might
39 overlook this detail when porting programs.
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41 More generally, the POSIX specification does not say anything about
42 file modes, so the application should make sure its umask is set appro‐
43 priately before calling mkstemp().
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46 4.3BSD, POSIX.1-2001
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49 The prototype is in <unistd.h> for libc4, libc5, glibc1; glibc2 follows
50 the Single Unix Specification and has the prototype in <stdlib.h>.
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53 mkdtemp(3), mktemp(3), tempnam(3), tmpfile(3), tmpnam(3)
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57GNU 2001-12-23 MKSTEMP(3)