STREROR(3)              BSD Library Functions Manual              STREROR(3)

NAME
     perror, strerror, strerrorr, syserrlist, sysnerr -- system error mes-
     sages

LIBRARY
     Standard C Library (libc, -lc)

SYNOPSIS
     ##include <>

     void
     perror(const char *string);

     extern const char * const syserrlist[];
     extern const int sysnerr;

     ##include <>

     char *
     strerror(int errnum);

     int
     strerrorr(int errnum, char *strerrbuf, sizet buflen);

DESCRIPTION
     The strerror(), strerrorr() 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 strerrorr() 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 cur-
     rent value of the global variable errno (intro(2)) and writes it, fol-
     lowed by a newline, to the standard error file descriptor.  If the argu-
     ment string is non-NUL 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
     printed.

     If the error number is not recognized, these functions return an error
     message string containing ``Unknown error: '' followed by the error num-
     ber in decimal.  The strerror() and strerrorr() functions return EINVAL
     as a warning.  Error numbers recognized by this implementation fall in
     the range 0 < errnum < sysnerr.

     If insufficient storage is provided in strerrbuf (as specified in buflen)
     to contain the error string, strerrorr() 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
     syserrlist.  The external value sysnerr contains a count of the mes-
     sages in syserrlist.  The use of these variables is deprecated;
     strerror() or strerrorr() should be used instead.

SEE ALSO
     intro(2), psignal(3)

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

HISTORY
     The strerror() and perror() functions first appeared in 4.4BSD.  The
     strerrorr() function was implemented in FreeBSD 4.4 by Wes Peters
     .

BUGS
     For unknown error numbers, the strerror() function will return its result
     in a static buffer which may 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 syserrlist variable often fail to com-
     pile because they declare it inconsistently.

BSD                            October 12, 2004                            BSD