    PERROR(III)                  11/5/73                  PERROR(III)

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

    SYNOPSIS
         perror(s)
         char *s;

         int sys_nerr;
         char *sys_errlist[];

         int errno;

    DESCRIPTION
         Perror produces a short error message  describing  the  last
         error  encountered during a call to the system from a C pro-
         gram.  First the argument string s is printed, then a colon,
         then  the  message and a new-line.  Most usefully, the argu-
         ment string is the name of the program  which  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 vector of
         message strings sys_errlist is provided; errno can  be  used
         as  an index in this table to get the message string without
         the newline.  Sys_nerr is the largest message number provid-
         ed  for 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
         Introduction to System Calls

    BUGS

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