To kick off the upcoming 4th of July celebrations we present the following bash script for your enjoyment.

Do you know what this sequence of characters "/-\|/-\|" is for? A text based spinner. Still confused, read on.

The trap statement in bash causes your script to execute one or more commands when a signal is received. One of the useful things you can use this for is to clean up temporary files when your script exits.

Using netstat, you can monitor programs that are making connections to remote hosts: $ netstat -tpe The -t flag limits the output to show only TCP connections. The -p flag displays the PID and name of the program making the connection. The -e flag displays extra information, such as the user name under which each program is running.

Generally when we think of shell scripts we think of editable text, but it's possible to add binary data to your shell script as well. In this case we're going to talk about adding a binary payload to the end of your shell script.

If you run a lot of terminal tabs or scripts that all need to make OpenSSH connections to the same server, you can speed them all up with multiplexing: making the first one act as the master and letting the others share its TCP connection to the server.

Using pyuno you can script OpenOffice with Python. Pyuno allows you to create macros inside OpenOffice and it also allows you to create external Python scripts that talk to a running copy of OpenOffice. If you want to get started with pyuno be prepared for an often frustrating experience: the documentation is sketchy and

Recently I needed to create a script that processed two input files. By processed I mean that the script needed to get a line from one file, then get a line from the second file, and then do something with them. Sounds easy enough, but it's not that easy unless you know about some of bash's extended redirection capabilities.

If you have a process ID but aren't sure whether it's valid, you can use the most unlikely of candidates to test it: the kill command. If you don't see any reference to this on the kill(1) man page, check the info pages. The man/info page states that signal 0 is special and that the exit code from kill tells whether a signal could be sent to the specified process (or processes).

A while back, I wrote an article for Linux Journal's web edition entitled “Howto be a good (and lazy) System Administrator.” A couple astute readers, after reading the article, asked if I was familiar with the Nagios monitoring system, and I am. I've been using Nagios for a few years now.