How to replace the first line using sed?

Question

Hi i am trying to replace the header line from my file using the sed command as mentioned below,

sed "1s/.*/$new_header/" Test_file.csv

The above line replaces the header and prints in stdout , But How can i redirect the output to new file or replace in the files directly ?

sed "1s/.*/$new_header/" Test_file.csv > new_file.csv

The above command works fine , But i want to redirect to same file.

Two related Q/A: How can I achieve portability with sed -i (in-place editing)? How to change a file in-place using awk? (as with "sed -i") — Kusalananda, May 20 '21 at 17:04

score 10 · Accepted Answer · edited May 20 '21 at 16:23

10

You can use -i flag to sed which will edit in-place and also take backup:

sed -i.bak "1 s/.*/$new_header/" inputfile

Note that the -i option is non-standard and may work differently in different implementations of sed. See How can I achieve portability with sed -i (in-place editing)?

edited May 20 '21 at 16:23

Kusalananda

answered Oct 18 '14 at 11:40

Rahul Patil

1 Answers1