Recipe: Text slicing and parameter operations

$ var = "This is a line of text"
$ echo ${var/line/REPLACED}
This is a REPLACED of text"

"line" is replaced with "REPLACED"


Producing sub string by specifying start position and string length
===================================================================
Syntax : 
${variable_name:start_position:length}

$ string=abcdefghijklmnopqrstuvwxyz
$ echo ${string:4}
efghijklmnopqrstuvwxyz
$ echo ${string:4:8}
efghijkl


echo ${string:(-1)}
z
echo ${string:(-8):2}
st