You can enter the "kill" command in a terminal if a process hangs.
kill ID
kill -9 ID
pkill firefox

You can switch to a virtual terminal using Ctrl + Alt + F1 if the user interface does not allow you to start the terminal.
This should hopefully restore some sanity to your computer and you can switch back to the GUI using Ctrl + Alt + F7

behave mswin - Copy and Paste with Ctrl+C CtrlV
set laststatus=2 - grey status bar at the bottom
syntax on - syntax highlighting
set autoindent - auto indenting
set number - line numbers
set showcmd - show command in status line
set showmatch - show matching brackets
set ignorecase - do case insensitive matching
set hlsearch - highlight what you search for

HashKnownHosts no
Add the above line in your ssh_config file that can be found here....
/etc/ssh/ssh_config

output redirection using n> usually overwrites existing files. You can control this with the noclobber option of the set builtin. If it has been set, you can override it using n>|

$ set -o noclobber
$ ls x* z* >stdout.txt 2>stderr.txt
-bash: stdout.txt: cannot overwrite existing file
$ ls x* z* >|stdout.txt 2>|stderr.txt
$ set +o noclobber

The following command can be used to send messages to remote servers.

ssh -X root@123.123.123.123 'DISPLAY=:0 notify-send "TEST MESSAGE."'

The command that actually sends the message is...
notify-send "hi vandana"

wget is really a very powerful utility. Here is an example.

wget -mk http://oksoft.antville.org

I can download all the pages linked from my blog. And it is so easy!

-m (--mirror) Turn on options suitable for mirroring. This option turns on recursion and time-stamping, sets infinite recursion depth and keeps FTP directory list‐ings. It is currently equivalent to -r -N -l inf --no-remove-listing.

-k (--convert-links) After the download is complete, convert the links in the document to make them suitable for local viewing.

Changing the -e to -i in the following can be disastrous. It will replace the character "g" from all text files found in current directory as well as subfolder.

$ find . -name "*.txt" -exec sed -e 's/g//g' {} \;

Be careful with sed's -i option

___

It can also be very useful to change a string across all files...

select.worldpay.com/wcc/purchase

replace this with the new string

select.wp3.rbsworldpay.com/wcc/purchase/

The command would be...
grep 'select.worldpay.com/wcc/purchase' . -Rl | xargs sed -i 's/select.worldpay.com\/wcc\/purchase/select.wp3.rbsworldpay.com\/wcc\/purchase/g'

I was looking for the file translate.html from my backup drives, e: and f:
Since it was taking some time on Windows system, I stared the live session of Ubuntu and used the following command after touching both the drives from "Places" menu.

find /media/ -name translate.html

Very fast and accurate results!

$ cat salaries
Yvette van der Hoff 100000
Sarack Abama 400000
Bernie Madoff 0
John Q. Public 20000

$ awk '{print $NF, $0}' salaries | sort -nr -k1,1 | cut -d" " -f2-
Sarack Abama 400000
Yvette van der Hoff 100000
John Q. Public 20000
Bernie Madoff 0

$ awk -F '\t' -v 'OFS=\t' '{print $4, $3, $5, $2, $1}' data.txt
POP. COUNTY GOVT. CITY STATE
123 Gila Mayor Ely AZ
345 Lolo Sheriff Alma CA
22 El Paso Bubba Leroy TX

Sick of your computer speaker beeping like a demented Morse code machine whenever you type something wrongly? Teach it the sound of silence: run the command
setterm -blength 0
to mute the alarm bell no matter what kind of terminal you're typing into.
If you want it to happen every time you start a terminal, just add the command to your .bash_profile file.