A chronological documentation test project, nothing serious, really!

30 Aug 2010 Redirect failing URLs to other webserver

A typical FAQ about URL rewriting is how to redirect failing requests on webserver A to webserver B. Usually this is done via ErrorDocument CGI-scripts in Perl, but there is also a mod_rewrite solution. But notice that this performs more poorly than using an ErrorDocument CGI-script!

Place this in your httpd.conf og .htaccess file on the domain you want to redirect HTTP requests from
This is one possible solution but less flexible, and is less error safe

RewriteEngine on
RewriteCond   /your/docroot/%{REQUEST_FILENAME} !-f
RewriteRule   ^(.+)                             http://webserverB.dom/$1

The problem here is that this will only work for pages inside the DocumentRoot.


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04 Jun 2007 How do I save or redirect stdout and stderr into different files?

Q. I need to run a program called However this program is run from cron job. It report error to stderr and normal output to stdout. How do I save stdout, stderr and both into 3 separate log files?

A. It is not that hard if you know howto redirect stderr, stdout and a small command called tee.

=> fd0 is stdin
=> fd1 is stdout
=> fd2 is stderr

There are two formats for redirecting standard output and standard error:

For example anything written to fd2 to the same place as output to fd1, you will use:

tee command read from standard input and write to standard output and file.

So to send stderr to /tmp/errors.log, stdout to /tmp/output.log and both to /tmp/final.log, type as follows:

((/path/to/ 2>&1 1>&3 | tee /tmp/errors.log) 3>&1 1>&2 | tee /tmp/output.log) > /tmp/final.log 2>&1

Read bash man page and tee command for more information.

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09 Feb 2007 someprog > /dev/null 2>&1

The first part, “> /dev/null” means send standard output to the ‘bit bucket” or in other words, throw it away.

The second part, “2>&1” means “redirect standard error (2) to the same place as standard outout (1.)

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