perror(3C)
print system error messages
From the original Amiga UNIX 2.1 manual. Some things it mentions may not be in this release.
NAME
perror - print system error messages
SYNOPSIS
#include <stdio.h> void perror (const char *s);
DESCRIPTION
perror produces a message on the standard error output (file descriptor 2), 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 newline. (However, if s is a null pointer or points to a null string, 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.
SEE ALSO
intro(2), fmtmsg(3C), strerror(3C).