[SOLVED] sed insert multiple lines before multiple lines pattern

Issue

I have the following very long file:

...
close unit 1
...
...
close unit 1
...
...
close unit 1

stop

I want to insert multiples lines before the last close unit 1 which is before stop. The file contains an undefined number of close unit 1.

I found a lot of other similar questions here and there, but the answers couldn't help me... For example I tried https://stackoverflow.com/a/8635732/1689664 but this didn't work...

Solution

Using sed and tac:

$ tac inputfile | sed '/close unit 1/ {s/\(.*\)/\1\nLine3\nLine2\nLine1/; :loop; n; b loop}' | tac
...
close unit 1
...
...
close unit 1
...
...
Line1
Line2
Line3
close unit 1

stop

Note that you'd need to specify the input lines in the reverse order in the sed expression.

Answered By - devnull