The command `cat file >> file` failes with the following error message:

cat: file: input file is output file

`tee` is a nice workaround without using any temporary files.

This will launch and irssi session on your server. If it's not running, it will create the session. If it's running it'll connect to it and destroy any other connections. If compositing is available, the rxvt window will have transparency added. This window will also open maximized. Anything else this does should be easily figured out in the man pages.

On a Gentoo system, this command will tell you which packets you have installed and sort them by how much space they consume. Good for finding out space-hogs when tidying up disk space.

Convert Text to HTML

Should work on all systems that use dpkg and APT package management.

Useful for deleting old unused log files.

Unmount

Delete loopback file device

If you use newsgroups then you'll have come across split files before. Joining together a whole batch of them can be a pain so this will do the whole folder in one.

Make ogg file from wav file

Rip audio tracks from CD to wav files in current dir

add (server-start) in .emacs

I'm working in a group project currently and annoyed at the lack of output by my teammates. Wanting hard metrics of how awesome I am and how awesome they aren't, I wrote this command up.

It will print a full repository listing of all files, remove the directories which confuse blame, run svn blame on each individual file, and tally the resulting line counts. It seems quite slow, depending on your repository location, because blame must hit the server for each individual file. You can remove the -R on the first part to print out the tallies for just the current directory.

Find Word docs by filename in the current directory, convert each of them to plain text using antiword (taking care of spaces in filenames), then grep for a search term in the particular file.

(Of course, it's better to save your data as plain text to make for easier grepping, but that's not always possible.)

Requires antiword. Or you can modify it to use catdoc instead.

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

A common mistake in Bash is to write command-line where there's command a reading a file and whose result is redirected to that file.

It can be easily avoided because of :

1) warnings "-bash: file.txt: cannot overwrite existing file"

2) options (often "-i") that let the command directly modify the file

but I like to have that small function that does the trick by waiting for the first command to end before trying to write into the file.

Lots of things could probably done in a better way, if you know one...

This just combines multiple mp3's into one mp3 file. Basically it is a easy join for mp3's