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 on the standard error, describing the last error encountered during a system call from a C program.  First the argument string s is printed, then a colon, then the message and a new-line.  To be of most use, the argument string should be 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 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 new-line.  Sys_nerr is the largest message number provided 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

intro(2). 

May 16, 1980