Git excludesfile for a branch

Question

I want to ignore certain files within a branch without having to rely on a tracked .gitignore file that will be overwritten during merges with other branches.

Answer 1

Here's a script I wrote to do this:

#!/bin/bash                                                                      

# This is designed to allow per-branch un-ignoring of certain files.
# Use case: Compiled CSS files on master to push to server.
# A special .gitignore file will be present on master at
# {$gitignorePath}/{$disabledMasterGitignoreName} and that file should 
# enable the css files using the ! flag. @https://git-scm.com/docs/gitignore

# When the branch specified by script parameters
# is checked out, {$gitignorePath}/{$disabledMasterGitignoreName} is 
# copied to .gitignore. 
# On other branches this gitignore file is named $disabledMasterGitignoreName, versioned,
# and {$gitignorePath}.gitignore will be deleted. Note, you must ignore 
# {$gitignorePath}.gitignore from your main .gitignore file
#
# To enable put this file in your path and call this script
# in .git/hooks/post-checkout with pass a list of single-space-separated branches that
# will enable the branch-specific .gitignore.

# One caveat is that you can only merge into the branch containing the .gitignore
# file. Otherwise you'll end up re-committing the files. This is fine if you are
# using gitflow and `master` contains your special .gitigore using the ! syntax
# that is un-ignoring files.
#
# Background: @http://stackoverflow.com/questions/29579546/git-excludesfile-for-a-branch

set -e                                                                           

gitignorePath='docroot/sites/all/themes'
disabledMasterGitignoreName='.gitignore_master--disabled'
#branchWithGitignoreEnabled='master'

branch=$(git rev-parse --abbrev-ref HEAD)

gitignoreRoot="$(git rev-parse --show-toplevel)/${gitignorePath}"

if [ -f "${gitignorePath}/.gitignore" ]
then
    masterGitignoreExists=true
fi

if [ -f "${gitignorePath}/${disabledMasterGitignoreName}" ]
then
    disabledMasterGitignoreExists=true
fi

IFS=' ' read -a params <<< "$@"

if [[ " ${params[@]} " =~ " ${branch} " ]]
then
  if [ $disabledMasterGitignoreExists ]
  then
    cp -f "${gitignoreRoot}/${disabledMasterGitignoreName}" "${gitignoreRoot}/.gitignore"
    echo "Enabled ${gitignorePath}/.gitignore"
  fi
elif [ $masterGitignoreExists ]
then
    rm -f "${gitignorePath}/.gitignore"
    if [ masterGitignoreExists ]
    then
      echo "Disabled ${gitignorePath}/.gitignore"
    fi
fi