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Define shell variable HISTIGNORE so that comments (lines starting with #) appear in shell history
I was surprised to find that with RedHat bash, I could not find any comment lines (begining with #) in my bash shell history. Surprised because in Mageia Linux this works. It turns out that RedHat's bash will keep comment lines if in my .bashrc, I define: export HISTIGNORE=' cd "`*: PROMPT_COMMAND=?*?' Why have comment lines in shell history? It's a handy and convenient way to make proto-commands (to be completed later) and for storing brief text data that is searchable in shell history.

Setting global redirection of STDERR to STDOUT in a script
You have a script where =ALL= STDERR should be redirected to STDIN and you don't want to add "2>&1" at the end of each command... E.G.: $ ls -al /foo/bar 2>&1 Than just add this piece of code at the beginning of your script! I hope this can help someone. :)

Simplification of "sed 'your sed stuff here' file > file2 && mv file2 file"

View ~/.ssh/known_hosts key information
Will return the SSH server key information for each host you have in your ~/.ssh/known_hosts file, including key size, key fingerprint, key IP address or domain name, and key type.

Dump bash command history of an active shell user.

Port Knocking!
Knock on ports to open a port to a service (ssh for example) and knock again to close the port. You have to install knockd. See example config file below. [options] logfile = /var/log/knockd.log [openSSH] sequence = 3000,4000,5000 seq_timeout = 5 command = /sbin/iptables -A INPUT -i eth0 -s %IP% -p tcp --dport 22 -j ACCEPT tcpflags = syn [closeSSH] sequence = 5000,4000,3000 seq_timeout = 5 command = /sbin/iptables -D INPUT -i eth0 -s %IP% -p tcp --dport 22 -j ACCEPT tcpflags = syn

Stop Flash from tracking everything you do.
Brute force way to block all LSO cookies on a Linux system with the non-free Flash browser plugin. Works just fine for my needs. Enjoy.

Monitor Linux/MD RAID Rebuild

Download all Phrack .tar.gzs

Check if a package is installed. If it is, the version number will be shown.
If the first two letters are "ii", then the package is installed. You can also use wildcards. For example, . $ dpkg -l openoffice* . Note that dpkg will usually not report packages which are available but uninstalled. If you want to see both which versions are installed and which versions are available, use this command instead: . $ apt-cache policy python


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