PERROR(3C)                                             PERROR(3C)



     NAME
          perror, errno, sys_errlist, sys_nerr - system error messages

     SYNOPSIS
          void perror (s)
          char *s;

          extern int errno;

          extern char *syserrlist[ ];

          extern int sysnerr;

     DESCRIPTION
          perror produces a message on the standard error output,
          describing the last error encountered during a call to a
          system or library function.  The argument string s is
          printed first, then a colon and a blank, then the message
          and a new-line.  (However, if s="" the colon is not
          printed.)  To be of most use, the argument string should
          include the name of the program that incurred the error.
          The error number is taken from the external variable errno,
          which is set when errors occur but not cleared when non-
          erroneous calls are made.

          To simplify variant formatting of messages, the array of
          message strings sys_errlist is provided; errno can be used
          as an index into this table to get the message string
          without the new-line.  Sys_nerr is the number of messages in
          the table; it should be checked because new error codes may
          be added to the system before they are added to the table.

     SEE ALSO
          intro(2).

     ORIGIN
          AT&T V.3


















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