EVOL.reverse

Ctrl + a - Jump to the start of the line
Ctrl + e - Jump to the end of the line

Ctrl + b - Move back a char
Ctrl + f - Move forward a char

Ctrl + k - cut to EOL, and then Ctrl + Y is yank (or paste) what you cut previously.

Ctrl + u - Delete backward from cursor.
Ctrl + w - Delete word by word in reverse.

Ctr + t - swapping of the last two chars. A common mistake while typing.

!$ = last argument of last command, for example:

user@system:mkdir /this/is/a/dir
user@system:cd !$

Esc-f - move forward by word.
Esc-b - move backward by word.

Here “2T” means Press TAB twice

$ 2T - All available commands(common)
$ (string)2T - All available commands starting with (string)
$ /2T - Entire directory structure including Hidden one
$ 2T - Only Sub Dirs inside including Hidden one
$ *2T - Only Sub Dirs inside without Hidden one
$ ~2T - All Present Users on system from "/etc/passwd"
$ $2T - All Sys variables
$ @2T - Entries from "/etc/hosts"
$ =2T - Output like ls or dir

A complete guide is available here.

A simple for loop..

#!/bin/sh

for x in `ipcs | cut -f 2 -d ' '`
do
        ipcrm -q $x
done

This script tries to remove any msg queues listed with ipcs.

Another example, this time with an if condition..

if [ ! -e "$file" ]       # Check if file exists.
  then
    echo "$file does not exist."; echo
    continue                # On to next.
   fi

Test if file exists:

if [ -f .bash_profile ]; then
    echo "You have a .bash_profile. Things are fine."
else
    echo "Yikes! You have no .bash_profile!"
fi

Reading text from stdin:

echo -n "Enter some text > "
read text
echo "You entered: $text"

And now with a timeout of 3 seconds:

echo -n "Hurry up and type something! > "
if read -t 3 response; then
    echo "Great, you made it in time!"
else
    echo "Sorry, you are too slow!"
fi

Kind of a simple menu:

echo -n "Enter a number between 1 and 3 inclusive > "
read character
if [ "$character" = "1" ]; then
    echo "You entered one."
else
    if [ "$character" = "2" ]; then
        echo "You entered two."
    else
        if [ "$character" = "3" ]; then
            echo "You entered three."
        else
            echo "You did not enter a number"
            echo "between 1 and 3."
        fi
    fi
fi

A more fancy menu:

selection=
until [ "$selection" = "0" ]; do
    echo ""
    echo "PROGRAM MENU"
    echo "1 - display free disk space"
    echo "2 - display free memory"
    echo ""
    echo "0 - exit program"
    echo ""
    echo -n "Enter selection: "
    read selection
    echo ""
    case $selection in
        1 ) df ;;
        2 ) free ;;
        0 ) exit ;;
        * ) echo "Please enter 1, 2, or 0"
    esac
done