Question

I am using GNU sed command (GNU sed version 4.2.1) for search and replace in file.
I want the input file to remain intact hence I am using sed’s file writing option.

Following is the command

sed -e "s/INSERT/UPDATE/w  output.txt" "input.txt"

But problem with above command is, it does not write the unmatched lines. i.e. the lines in which the text to be searched if not found then that line is not getting written in output.txt file.

I want unmatched lines to be written in output.txt

how this can be achieved?

Answer 1

Use w as a separate command, i.e.:

sed -e 's/INSERT/UPDATE/' -e 'w output.txt' input.txt

or, if your sed supports it, you can use a semicolon:

sed -e 's/INSERT/UPDATE/;w output.txt' input.txt

But, if you really just want the output in a file, use redirection:

sed -e 's/INSERT/UPDATE/' input.txt > output.txt