Combine grep -v with grep -r?

Question

I want to remove an entire line of text from all files in a given directory. I know I can use grep -v foo filename to do this one file at a time. And I know I can use grep -r foo to search recursively through a directory. How do I combine these commands to remove a given line of text from all files in a directory?

@jlhonora this works but only prints everything to terminal and doesn't overwrite the actual file. — PGilbert, Aug 10 '15 at 20:13
@Sandeep do you know what the equivalent of grep -v is with sed? I looked here ( http://www.grymoire.com/Unix/Sed.html#uh-62m ) but couldn't find it. — PGilbert, Aug 10 '15 at 20:16
@Sandeep This works on a singular file basis: `sed 's/regexp/replacement/g' inputFileName > outputFileName` but I don't know how to do this across a directory of files. — PGilbert, Aug 10 '15 at 20:25
@PGilbert you'll need to combine sed with xargs. See my answer — jlhonora, Aug 10 '15 at 21:23

jlhonora · Answer 1 · 2015-08-11T00:04:26.830

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Try something like:

grep -vlre 'foo' . | xargs sed -i 's/pattern/replacement/g'

Broken down:

grep:
  -v 'Inverse match'
  -l 'Show filename'
  -r 'Search recursively'
  -e 'Extended pattern search'

xargs: For each entry perform

sed -i: replace inline

edited Aug 11 '15 at 00:04

answered Aug 10 '15 at 21:23

jlhonora

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I get the same error message as mentioned in my comment above. – PGilbert Aug 11 '15 at 01:41

score 1 · Answer 2 · answered Aug 10 '15 at 21:57

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The UNIX command to find files is named find, not grep. Forget you ever heard of grep -r as it's just a bad idea, here's the right way to find files and perform some action on them:

find . -type f -print | xargs sed -i '/badline/d'

answered Aug 10 '15 at 21:57

Ed Morton

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But what if you want to edit **only** the files that **don't contain** a certain keyword? That's what I understood from the question, and that's why I suggested `grep -rv` – jlhonora Aug 11 '15 at 00:01
This almost works, but I get the following error `sed: 1: "./hr1_14_s.nex": invalid command code .` where hr1_14_s.nex is the name of the file I want to search inside of. Here is a link to a test file so that maybe the error can be recreated. https://github.com/PrincessG/SignalNoise/blob/master/Testfile. I'd like to remove the entire lines containing 'alligator_mississippiensis'. – PGilbert Aug 11 '15 at 01:16
change `-i` to `-i ""` as you're apparently using a sed that requires `-i` to have an arg after it (OSX?). – Ed Morton Aug 11 '15 at 16:25
@jlhonora the script I posted will only make changes to files that contain the keyword. – Ed Morton Aug 11 '15 at 16:27

score 0 · Accepted Answer · edited May 23 '17 at 11:51

I think this would work:

grep -ilre 'Foo' . | xargs sed -i 'extension' 'Foo/d'

Where 'extension' refers to the addition to the file name. It will make a copy of the original file with the extension you designated and the modified file will have the original filename. I added -i in case you require it to be case insensitive.

modified file1 becomes "file1" original file1 becomes "file1extension"

invalid command code ., despite escaping periods, using sed

One of the responses suggests that the newer version of sed's -i option in OSX is slightly different so you need to add an extension. The file is being interpreted as a command, which is why you are seeing that error.

Combine grep -v with grep -r?

3 Answers3