SED : Tutorial 1

REF: http://www.grymoire.com/Unix/Sed.html

$echo day | sed s/day/night/
Output: night

$echo Sunday | sed 's/day/night/'
Output: Sunnight

slash/underscore/colon as a delimiter
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$echo "/home/fawad/sed" | sed 's/\/home\/fawad\/sed/\/home\/nazir\/fawad/'
Output: /home/nazir/fawad

$echo "/home/fawad/sed" | sed 's_/home/fawad/sed_/home/nazir/fawad_'
Output: /home/nazir/fawad

$echo "/home/fawad/sed" | sed 's:/home/fawad/sed:/home/nazir/fawad:'
Output: /home/nazir/fawad

Using & as the matched string
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$echo "123 Fawad Nazir" | sed 's/F[a-z]*/(&)/'
Output: 123 (Fawad) Nazir

The values is saved in &. So now you can use it in different ways...

$echo "123 Fawad Nazir" | sed 's/F[a-z]*/(&) [&] _&_ *&*/'
Output: 123 (Fawad) [Fawad] _Fawad_ *Fawad* Nazir

Fun: Only Print a and nothing else
$echo "Fawad Nazir Is a Great Man hahahaha" | sed s/[^a]/\ /g
Output: a a a a a a a a a a