1STRERROR(3)                Linux Programmer's Manual               STRERROR(3)
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NAME

6       strerror, strerror_r - return string describing error number
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SYNOPSIS

9       #include <string.h>
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11       char *strerror(int errnum);
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13       char *strerror_r(int errnum, char *buf, size_t buflen);
14                               /* GNU-specific strerror_r() */
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16       #define _XOPEN_SOURCE 600
17       #include <string.h>
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19       int strerror_r(int errnum, char *buf, size_t buflen);
20                               /* XSI-compliant strerror_r() */
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DESCRIPTION

23       The  strerror()  function  returns  a  string describing the error code
24       passed in the argument errnum, possibly using the LC_MESSAGES  part  of
25       the  current  locale  to  select the appropriate language.  This string
26       must not be modified by the application, but may be modified by a  sub‐
27       sequent  call to perror() or strerror().  No library function will mod‐
28       ify this string.
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30       The strerror_r() function is similar to strerror(), but is thread safe.
31       This  function  is  available in two versions: an XSI-compliant version
32       specified in POSIX.1-2001, and a GNU-specific version (available  since
33       glibc  2.0).   If _XOPEN_SOURCE is defined with the value 600, then the
34       XSI-compliant version is provided, otherwise the  GNU-specific  version
35       is provided.
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37       The  XSI-compliant strerror_r() is preferred for portable applications.
38       It returns the error string in the user-supplied buffer buf  of  length
39       buflen.
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41       The  GNU-specific strerror_r() returns a pointer to a string containing
42       the error message.  This may be either a pointer to a string  that  the
43       function  stores in buf, or a pointer to some (immutable) static string
44       (in which case buf is unused).  If the function stores a string in buf,
45       then  at  most  buflen bytes are stored (the string may be truncated if
46       buflen is too small) and the string always includes a terminating  null
47       byte.
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RETURN VALUE

51       The  strerror() and strerror_r() functions return the appropriate error
52       description string, or an "Unknown error nnn" message if the error num‐
53       ber is unknown.
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55       The XSI-compliant strerror_r() function returns 0 on success; on error,
56       -1 is returned and errno is set to indicate the error.
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ERRORS

60       EINVAL The value of errnum is not a valid error number.
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62       ERANGE Insufficient storage was supplied to contain the error  descrip‐
63              tion string.
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CONFORMING TO

67       strerror()  is  specified  by  POSIX.1-2001, C89, C99.  strerror_r() is
68       specified by POSIX.1-2001.
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70       The GNU-specific strerror_r() function is a non-standard extension.
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72       POSIX.1-2001 permits strerror() to set errno if the call encounters  an
73       error,  but does not specify what value should be returned as the func‐
74       tion result in the event of an  error.   On  some  systems,  strerror()
75       returns  NULL  if  the error number is unknown.  On other systems, str‐
76       error() returns a string something like "Error nnn occurred"  and  sets
77       errno to EINVAL if the error number is unknown.
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SEE ALSO

81       err(3),    errno(3),    error(3),    perror(3),    strsignal(3),   fea‐
82       ture_test_macros(7)
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86                                  2005-12-13                       STRERROR(3)
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