A start would be to just tell those of us who have never heard of it a bit about it.
PERROR(3) Library functions PERROR(3) NAME perror - print a system error message SYNOPSIS #include <stdio.h> void perror(const char *s); #include <errno.h> const char *sys_errlist[]; int sys_nerr; DESCRIPTION The routine perror() produces a message on the standard error output, describing the last error encountered during a call to a system or library function. First (if s is not NULL and *s is not NUL) the argument string s is printed, followed by a colon and a blank. Then the mes- sage and a new-line. To be of most use, the argument string should include the name of the function 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. The global error list sys_errlist[] indexed by errno can be used to obtain the error message without the newline. The largest message number provided in the table is sys_nerr -1. Be careful when directly accessing this list because new error values may not have been added to sys_errlist[]. When a system call fails, it usually returns -1 and sets the variable errno to a value describing what went wrong. (These values can be found in <errno.h>.) Many library functions do likewise. The function perror() serves to translate this error code into human-readable form. Note that errno is undefined after a successful library call: this call may well change this variable, even though it succeeds, for example because it internally used some other library function that failed. Thus, if a failing call is not immediately followed by a call to perror, the value of errno should be saved. CONFORMING TO ANSI C, BSD 4.3, POSIX, X/OPEN SEE ALSO strerror(3) 2001-12-14 PERROR(3)
And here's a way one might do it in Perl:
package PError; use strict; use warnings; our ($VERSION) = q $Revision: 1.1 $ =~ /([\d.]+)/g; sub perror {warn @_ ? "@_: $!\n" : "$!\n"} sub pdie {die @_ ? "@_: $!\n" : "$!\n"} my %symbols = map {$_ => 1} qw /perror pdie/; sub import { my $class = shift; my $caller = caller; foreach my $name (@_ ? @_ : keys %symbols) { die "'$name' is not exported.\n" unless $symbols {$name}; my $func = $name eq "pwarn" ? "perror" : $name; no strict 'refs'; *{$caller . "::$name"} = \&{$class . "::$func"} } } 1; __END__
when files arent there its usually a serious matter and I want to be able to track it back from the line it died from.I guess you and I differ. If a file is missing, than I will investigate why the file isn't there, and I'll start at the place that's supposed to produce the file. A line number in the program that figured out the file wasn't there doesn't do much for me.
Abigail
In reply to Re: Perl Style: About error messges opening files
by Abigail-II
in thread Perl Style: About error messges opening files
by demerphq
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