STRERROR(3)                    Library Routines                    STRERROR(3)




NAME

       perror, strerror, sys_errlist, sys_nerr, _errnoText - system error mes-
       sages


SYNOPSIS

       #include <stdio.h>

       void perror(const char *string);

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

       #include <string.h>

       char * strerror(int errnum);


DESCRIPTION

       The strerror and perror functions look up the error message string cor-
       responding to an error number.

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

       The perror function finds the error message corresponding to  the  cur-
       rent  value  of the global variable errno (see intro(2)) and writes it,
       followed by a newline, to the standard error file descriptor.   If  the
       argument  string is non-NULL, it is prepended to the message string and
       separated from it by a colon and space.  If string is  NULL,  only  the
       error message string is printed.

       If  errnum  is  not a recognized error number, the error message string
       will contain unknown error:, followed by the error number in decimal.

       The message strings can be accessed directly using the  external  array
       sys_errlist.   The external value sys_nerr contains a count of the mes-
       sages in sys_errlist.  For backwards compatibility with older  versions
       of  GNO,  sys_errlist  can  also  be  referenced  through  the variable
       _errnoText, which has identical type.  The use of  these  variables  is
       deprecated; strerror should be used instead.


SEE ALSO

       intro(2), psignal(3)


HISTORY

       The strerror and perror functions first appeared in 4.4BSD.


BUGS

       For unknown error numbers, the strerror function will return its result
       in a static buffer which may be overwritten by subsequent calls.

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



GNO                            22 December 1997                    STRERROR(3)

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