Saturday 15 June 2019

How to grep (search) committed code in the Git history



I have deleted a file or some code in a file sometime in the past. Can I grep in the content (not in the commit messages)?



A very poor solution is to grep the log:



git log -p | grep 



However, this doesn't return the commit hash straight away. I played around with git grep to no avail.


Answer



To search for commit content (i.e., actual lines of source, as opposed to commit messages and the like), you need to do:



git grep  $(git rev-list --all)


git rev-list --all | xargs git grep will work if you run into an "Argument list too long" error.




If you want to limit the search to some subtree (for instance, "lib/util"), you will need to pass that to the rev-list subcommand and grep as well:



git grep  $(git rev-list --all -- lib/util) -- lib/util


This will grep through all your commit text for regexp.



The reason for passing the path in both commands is because rev-list will return the revisions list where all the changes to lib/util happened, but also you need to pass to grep so that it will only search in lib/util.




Just imagine the following scenario: grep might find the same on other files which are contained in the same revision returned by rev-list (even if there was no change to that file on that revision).



Here are some other useful ways of searching your source:



Search working tree for text matching regular expression regexp:



git grep 


Search working tree for lines of text matching regular expression regexp1 or regexp2:




git grep -e  [--or] -e 


Search working tree for lines of text matching regular expression regexp1 and regexp2, reporting file paths only:



git grep -e  --and -e 


Search working tree for files that have lines of text matching regular expression regexp1 and lines of text matching regular expression regexp2:




git grep -l --all-match -e  -e 


Search working tree for changed lines of text matching pattern:



git diff --unified=0 | grep 


Search all revisions for text matching regular expression regexp:




git grep  $(git rev-list --all)


Search all revisions between rev1 and rev2 for text matching regular expression regexp:



git grep  $(git rev-list ..)

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