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Remove all unused kernels with apt-get
A little aptitude magic. Note: this will remove images AND headers. If you just want to remove images: aptitude remove ?and(~i~nlinux-im ?not(~n`uname -r`)) I used this in zsh without any problems. I'm not sure how other shells will interpret some of the special characters used in the aptitude search terms. Use -s to simulate.

xargs for builtin bash commands
Similar to xargs -i, but works with builtin bash commands (rather than running "bash -c ..." through xargs)

Read and write to TCP or UDP sockets with common bash tools
Ever needed to test firewalls but didn't have netcat, telnet or even FTP? Enter /dev/tcp, your new best friend. /dev/tcp/(hostname)/(port) is a bash builtin that bash can use to open connections to TCP and UDP ports. This one-liner opens a connection on a port to a server and lets you read and write to it from the terminal. How it works: First, exec sets up a redirect for /dev/tcp/$server/$port to file descriptor 5. Then, as per some excellent feedback from @flatcap, we launch a redirect from file descriptor 5 to STDOUT and send that to the background (which is what causes the PID to be printed when the commands are run), and then redirect STDIN to file descriptor 5 with the second cat. Finally, when the second cat dies (the connection is closed), we clean up the file descriptor with 'exec 5>&-'. It can be used to test FTP, HTTP, NTP, or can connect to netcat listening on a port (makes for a simple chat client!) Replace /tcp/ with /udp/ to use UDP instead.

Refresh the cache of font directory
Refresh the cache of font directory , usefull after you download font (.ttf or other) from various website and you don't want to reboot or relogin . Close your word processor before using the command , after the refresh reopen your word processor , new fonts is avaible !

Start dd and show progress every X seconds
Adjust "sleep X" to your needs. *NOTE: First sleep is required because bash doesn't have a "post-test" syntax (do XXX while).

Make vim open in tabs by default (save to .profile)
I always add this to my .profile rc so I can do things like: "vim *.c" and the files are opened in tabs.

Create a mirror of a local folder, on a remote server
Create a exact mirror of the local folder "/root/files", on remote server 'remote_server' using SSH command (listening on port 22) (all files & folders on destination server/folder will be deleted)

hard disk information - Model/serial no.
Get the hard disk information with out shutting down and opening the system. It gives information on model no., serial no., cylinders/heads/sectors, and the supported features of the hard disk.

View a file with less, starting at the end of the file
The same as typing 'less filename' then 'G' or '>' or the END key. Comes in handy with shell scripts or aliases: alias weblog='less +G /var/log/httpd/access_log' alias errlog='less +G /var/log/httpd/error_log'

A little bash daemon =)
A little bash daemon


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