Simple Example of Unix "sed" command

Replacing all occurrences of rakesh to raka in file tst

sed s/rakesh/raka/ tst-1

Replacing all occurences of "raka" in old file tst-1 to "rakesh" in new file tst-2

sed s/raka/rakesh/ < tst-1 > tst-2

$ echo rakesh | sed s/rakesh/raka/

raka

$ echo I am rakesh | sed s/rakesh/raka/

I am raka

$ echo I am rakesh | sed 's/rakesh/raka/'

I am raka

s: Substitute Command

/../../ : Delimiter

rakesh : Regular Expression Pattern Search Pattern

raka : Replacement String

$ sed 's/\/tmp\/rk/\/tmp\/rk\/1/' tst-1

hi rakesh parwal

here is the directory /tmp/rk/1