How do you delete all lines that begin with "string" in unix sh?

Question

How do you delete all lines in a file that begin with "string" in sh? I was thinking about using the sed command.

score 37 · Accepted Answer · answered Nov 09 '11 at 16:34

37

grep -v '^string' yourfile.txt > stripped.txt

answered Nov 09 '11 at 16:34

Marc B

how about out of the same file? – t3hcakeman Nov 09 '11 at 16:37
Can't really do that with grep. but you could output to a temp file then `mv tempfile origfile`. If you want true in-place editing, then sed/perl/awk would need to be used. – Marc B Nov 09 '11 at 16:39
how would I use those then? :D – t3hcakeman Nov 09 '11 at 16:41
1

http://ptankov.wordpress.com/2008/04/09/howto-delete-a-line-in-place-with-gnu-sed/ – Marc B Nov 09 '11 at 16:42
didn't work, only reprinted the lines EXCEPT the lines containing the string – t3hcakeman Nov 09 '11 at 17:00
actually that was my error, it DID how ever make a new file with the filename plus -e at the end of the extension – t3hcakeman Nov 09 '11 at 18:02
Use `| sponge $inputfile` from the package `moreutils` to use the same file – trallnag May 17 '20 at 14:02

score 36 · Answer 2 · answered Nov 09 '11 at 16:45

36

To do it in place, if your sed supports the -i option, you can do:

sed -i '/^string/d' input-file

answered Nov 09 '11 at 16:45

William Pursell

4

sed is expecting a file extension for backup when using `-i`, in OS X you must be very pedantic, so explicitly use single quotes: `sed -i '' '/^string/d' input-file` – Joel Bruner Sep 23 '13 at 17:49
3

In OSX, the default `sed` doesn't even support `-i`! My personal preference is to never use `-i` and do redirections with the shell instead. – William Pursell Sep 23 '13 at 22:01
No `-e` needed? – Mausy5043 Nov 12 '17 at 17:36
It doens't work in ksh? If text has line as 'string-d' then? doesn't work – rohansr002 Jan 30 '20 at 13:03

score 3 · Answer 3 · answered Nov 09 '11 at 17:39

3

sed and grep in your answers are missing their friend awk:

awk '!/^string/' inputfile > resultfile

answered Nov 09 '11 at 17:39

Kent

score 1 · Answer 4 · answered Nov 05 '16 at 14:50

1

You can use Vim in Ex mode:

ex -sc g/^string/d -cx file

answered Nov 05 '16 at 14:50

Zombo

4 Answers4