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Standard error is an standard output stream where a program may write its error messages.
The following snippets show how to do this using various languages.
Snippets
C
#include <stdio.h> fprintf(stderr, "something broke :-(\n");
C++
#include <iostream>
std::cerr << "something broke :-(" << std::endl;
C#
System.Console.Error.WriteLine("something broke :-(");
Java
System.err.println("something broke :-(");
OCaml
prerr_endline "something broke :-(";
Printf.eprintf "something broke :-(\n";
Perl
print STDERR "something broke :-(\n";
PHP
When using PHP in CLI mode (Command Line Interface), you can send error messages to stderr:
fputs(STDERR, 'Error!'); // sends 'Error!' to stderr
Under a webserver, the STDERR stream is usually linked to the web server's error log.
Python
2.x
import sys
print >> sys.stderr, "something broke :-("
sys.stderr.write("something broke :-(") # no trailing newline
3.x
import sys
print("something broke :-(", file=sys.stderr)
Ruby
To just write to standard error:
$stderr.puts("Error goes here")
If you want to create an IO object and point that to standard error:
# the file descriptor 2 = standard error
errors = IO.new(2, "w")
errors.puts("Error goes here")
Tcl
puts stderr "An error message"
External links
- Standard streams at Wikipedia