44

I want to delete a line containing a specific string from the file. How can I do this without using awk? I tried to use sed but I could not achieve it.

Brian Tompsett - 汤莱恩
  • 5,753
  • 72
  • 57
  • 129
virtue
  • 583
  • 2
  • 8
  • 11

3 Answers3

71

This should do it:

sed -e s/deletethis//g -i *
sed -e "s/deletethis//g" -i.backup *
sed -e "s/deletethis//g" -i .backup *

it will replace all occurrences of "deletethis" with "" (nothing) in all files (*), editing them in place.

In the second form the pattern can be edited a little safer, and it makes backups of any modified files, by suffixing them with ".backup".

The third form is the way some versions of sed like it. (e.g. Mac OS X)

man sed for more information.

mvds
  • 45,755
  • 8
  • 102
  • 111
  • I think it is usually a better idea to quote the expression and in addition I'd like to point out the `-i.bak` syntax where sed creates a backup file with the extension given. I.e. could be `-i.backup`, too ... – 0xC0000022L Apr 07 '11 at 16:40
  • 1
    @STATUS you're right, some versions of sed actually need the suffix. – mvds Apr 07 '11 at 16:42
  • 3
    This does not work.This deletes string.I want to delete line that contains this string – virtue Apr 07 '11 at 16:59
  • 6
    It does work. It answers your question. You could use `grep -v` if you want to simply drop lines containing a certain string. – mvds Apr 07 '11 at 17:23
  • 1
    This is working in busibox, while `sed -i '/pattern/d'` does not (removes all the line, not the string) – danius Jan 28 '18 at 15:53
  • Used this in `zsh` on Mac OS to get it to work I had to add double quotes but worked fine on entire directory: `sed -e "s/
    //g" -i *`     – james-see Jun 08 '20 at 19:18
36
sed -i '/pattern/d' file

Use 'd' to delete a line. This works at least with GNU-Sed.

If your Sed doesn't have the option, to change a file in place, maybe you can use an intermediate file, to store the modification:

sed '/pattern/d' file > tmpfile && mv tmpfile file

Writing directly to the source doesn't work: sed '/pattern/d' FILE > FILE so make a copy before trying out, if you doubt it. The redirection to a new file FILE will open a new file FILE before reading from it, so reading from it will result in an empty input.

user unknown
  • 35,537
  • 11
  • 75
  • 121
  • 2
    This is the correct answer to the original question. For safety reasons, you could use `-i.bak` instead of just `-i` to create a backup of your original file. – Mike Jan 26 '17 at 14:05
  • This is not working on busybox's `sed`, it removes all the line not the string, @mvds answer works – danius Jan 28 '18 at 15:52
  • @danigosa: Well, that's why mvds answer is wrong, The question was, to remove a line, not the string. Read the question, read the comment of virtue in the most upvoted answer. – user unknown Jan 29 '18 at 02:44
  • 1
    Didn't work on macOS. Had to do `sed 's/pattern//g'` – pedromss Dec 27 '19 at 17:04
  • @pedromss: That's for deleting a word, not the line containing the word. – user unknown Dec 28 '19 at 03:45
  • This seems to delete the line before the word too for me – Freedo Mar 28 '20 at 09:17
  • @Freedo: Please note the different topic of headline and question text. – user unknown Mar 28 '20 at 16:26
  • @pedromss, your code is good for test to print to stdout, but not to change the file if your os supports the use of the i flag. – Timo Nov 03 '20 at 17:18
2

Try the vim-way:

ex -s +"g/foo/d" -cwq file.txt
kenorb
  • 155,785
  • 88
  • 678
  • 743