1CONFSTR(3) Linux Programmer's Manual CONFSTR(3)
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6 confstr - get configuration dependent string variables
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9 #define _POSIX_C_SOURCE 2
10 or
11 #define _XOPEN_SOURCE
12 #include <unistd.h>
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14 size_t confstr(int name, char *buf, size_t len);
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17 confstr() gets the value of configuration-dependent string variables.
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19 The name argument is the system variable to be queried. The following
20 variables are supported:
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22 _CS_GNU_LIBC_VERSION (GNU C library only; since glibc 2.3.2)
23 A string which identifies the GNU C library version on this sys‐
24 tem (e.g, "glibc 2.3.4").
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26 _CS_GNU_LIBPTHREAD_VERSION (GNU C library only; since glibc 2.3.2)
27 A string which identifies the POSIX implementation supplied by
28 this C library (e.g, "NPTL 2.3.4" or "linuxthreads-0.10").
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30 _CS_PATH
31 A value for the PATH variable which indicates where all the
32 POSIX.2 standard utilities can be found.
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34 If buf is not NULL and len is not zero, confstr() copies the value of
35 the string to buf truncated to len - 1 characters if necessary, with a
36 null byte ('\0') as terminator. This can be detected by comparing the
37 return value of confstr() against len.
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39 If len is zero and buf is NULL, confstr() just returns the value as
40 defined below.
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43 If name is a valid configuration variable, confstr() returns the number
44 of bytes (including the terminating null byte) that would be required
45 to hold the entire value of that variable. This value may be greater
46 than len, which means that the value in buf is truncated.
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48 If name is a valid configuration variable, but that variable does not
49 have a value, then confstr() returns 0. If name does not correspond to
50 a valid configuration variable, confstr() returns 0, and errno is set
51 to EINVAL.
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54 EINVAL If the value of name is invalid.
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57 The following code fragment determines the path where to find the
58 POSIX.2 system utilities:
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60 char *pathbuf; size_t n;
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62 n = confstr(_CS_PATH,NULL,(size_t)0);
63 if ((pathbuf = malloc(n)) == NULL) abort();
64 confstr(_CS_PATH, pathbuf, n);
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67 POSIX.1-2001
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70 sh(1), exec(3), system(3), feature_test_macros(7)
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74GNU 1993-04-17 CONFSTR(3)