Commands by joesse (1)

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Interactively build regular expressions
txt2regex can be interactive or noninteractive and generates regular expressions for a variety of dialects based on user input. In interactive mode, the regex string builds as you select menu options. The sample output here is from noninteractive mode, try running it standalone and see for yourself. It's written in bash and is available as the 'txt2regex' package at least under debian/ubuntu.

Suppress output of loud commands you don't want to hear from
This works even if there are spaces in any word in the command line.

Which processes are listening on a specific port (e.g. port 80)
swap out "80" for your port of interest. Can use port number or named ports e.g. "http"

Print ASCII Character Chart
Prints out an ascii chart using builtin bash! Then formats using cat -t and column. The best part is: $ echo -e "${p: -3} \\0$(( $i/64*100 + $i%64/8*10 + $i%8 ))"; From: http://www.askapache.com/linux/ascii-codes-and-reference.html

Getting started with tcpdump
At some point you want to know what packets are flowing on your network. Use tcpdump for this. The man page is obtuse, to say the least, so here are some simple commands to get you started. -n means show IP numbers and don't try to translate them to names. -l means write a line as soon as it is ready. -i eth0 means trace the packets flowing through the first ethernet interface. src or dst w.x.y.z traces only packets going to or from IP address w.x.y.z. port 80 traces only packets for HTTP. proto udp traces only packets for UDP protocol. Once you are happy with each option combine them with 'and' 'or' 'not' to get the effects you want.

Convert wmv into avi

View Processeses like a fu, fu
I don't truly enjoy many commands more than this one, which I alias to be ps1.. Cool to be able to see the heirarchy and makes it clearer what need to be killed, and whats really going on.

Null a file with sudo

Force the script to be started as root
Place this code at the beginning of your script to ensure that it can only be executed by the root.

analyze traffic remotely over ssh w/ wireshark
Please check out my blog article on this for more detail. http://jdubb.net/blog/2009/08/07/monitor-wireshark-capture-real-time-on-remote-host-via-ssh/

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