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STRERROR(3)            FreeBSD Library Functions Manual            STRERROR(3)

     perror, strerror, strerror_r, sys_errlist, sys_nerr - system error

     Standard C Library (libc, -lc)

     #include <stdio.h>

     perror(const char *string);

     extern const char * const sys_errlist[];
     extern const int sys_nerr;

     #include <string.h>

     char *
     strerror(int errnum);

     strerror_r(int errnum, char *strerrbuf, size_t buflen);

     The strerror(), strerror_r() and perror() functions look up the error
     message string corresponding to an error number.

     The strerror() function accepts an error number argument errnum and
     returns a pointer to the corresponding message string.

     The strerror_r() function renders the same result into strerrbuf for a
     maximum of buflen characters and returns 0 upon success.

     The perror() function finds the error message corresponding to the
     current value of the global variable errno (intro(2)) and writes it,
     followed by a newline, to the standard error file descriptor.  If the
     argument string is non-NULL and does not point to the null character,
     this string is prepended to the message string and separated from it by a
     colon and space (``: ''); otherwise, only the error message string is

     If the error number is not recognized, these functions return an error
     message string containing ``Unknown error: '' followed by the error
     number in decimal.  The strerror() and strerror_r() functions return
     EINVAL as a warning.  Error numbers recognized by this implementation
     fall in the range 0 < errnum < sys_nerr.  The number 0 is also
     recognized, although applications that take advantage of this are likely
     to use unspecified values of errno.

     If insufficient storage is provided in strerrbuf (as specified in buflen)
     to contain the error string, strerror_r() returns ERANGE and strerrbuf
     will contain an error message that has been truncated and NUL terminated
     to fit the length specified by buflen.

     The message strings can be accessed directly using the external array
     sys_errlist.  The external value sys_nerr contains a count of the
     messages in sys_errlist.  The use of these variables is deprecated;
     strerror() or strerror_r() should be used instead.

     intro(2), err(3), psignal(3)

     The perror() and strerror() functions conform to ISO/IEC 9899:1999
     (``ISO C99'').  The strerror_r() function conforms to IEEE Std
     1003.1-2001 (``POSIX.1'').

     The strerror() and perror() functions first appeared in 4.4BSD.  The
     strerror_r() function was implemented in FreeBSD 4.4 by Wes Peters
     <[email protected]>.

     The strerror() function returns its result in a static buffer which will
     be overwritten by subsequent calls.

     The return type for strerror() is missing a type-qualifier; it should
     actually be const char *.

     Programs that use the deprecated sys_errlist variable often fail to
     compile because they declare it inconsistently.

FreeBSD 11.1-RELEASE-p4          April 5, 2011         FreeBSD 11.1-RELEASE-p4
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