Can a Git hook automatically add files to the commit?

Question

I\'d like to add an automatically generated file to the same commit using a pre- or post-commit hook in Git, dependent on the files that were modified in that commit. How w

Answer 1

Since git add was also not working for me in a pre commit, I followed mark's idea of using a .commit file and splitting the process into pre- and post-commit.

Here is some code that should be easy to understand

In the pre-commit:

• Touch a file .commit or something. (be sure to add this to .gitignore)

#!/bin/sh 
echo 
touch .commit 
exit

In the post-commit:

if .commit exists you know a commit has just taken place but a post-commit hasn't run yet. So, you can do your code generation here. Additionally, test for .commit and if it exists:

• add the files
• commit --amend -C HEAD --no-verify (avoid looping)
• delete .commit file

#!/bin/sh
echo
if [ -e .commit ]
    then
    rm .commit
    git add yourfile
    git commit --amend -C HEAD --no-verify
fi
exit

Hope this makes it easier for people with few bash knowledge to follow mark's idea.

Answer 2

I had the same need and this approach worked pretty well for me:

#!/bin/sh
files='git diff --cached --name-only'
re="<files of importance>"
if [[ $files =~ $re ]]
then
   echo "Creating files"
   create_my_files && git add my_files
fi

where "create_my_files" should be executable, for example if it is a python file you could execute it as "python create_my_files && git add my_files"

and is true you don't need a pre-commit to commit again (that would create a infinite nasty loop :p)

Answer 3

It's possible to do what you want using pre-commit hooks. We do something similar for a heroku deployment (compiling coffeescript to javascript). The reason your script isn't working is because you used the exec command improperly.

From the man page:

The exec builtin is used to replace the currently running shells process image with a new command. On successful completion, exec never returns. exec can not be used inside a pipeline.

Only your first exec command is running. After that your script is basically terminated.

Give something like this a try (as a pre-commit hook):

#!/bin/sh
files=`git diff --cached --name-status`
re="<files of importance>"
if [[ $files =~ $re ]]
then
  echo "Creating files"
  bundle exec create_my_files
  git add my_files
fi

Answer 4

You could use a combination of a pre and post commit script.

In the pre-commit:

• Touch a file .commit or something. (be sure to add this to .gitignore)

In the post-commit:

if .commit exists you know a commit has just taken place but a post-commit hasn't run yet. So, you can do your code generation here. Additionally, test for .commit and if it exists:

• add the files
• commit --ammend -C HEAD --no-verify (avoid looping)
• delete .commit file

This is roughly the process I use to store a .metadata file in the repository generated from metastore.

If anyone knows a better way I'm all ears but it seems to work for now.

Answer 5

You can use update-index:

git update-index --add my_files

Answer 6

I was facing same problem in pre-commit hook also. I was modifying one file and committing but it was taking previous file not updated file so by adding git command(as below) in pre-commit hook, it solved.

git add $file

note: $file is your file to be added.

Thanks,