How to update a file across all branches in a Git repository

Question

In the case that a a repository has a number of branches: How does one simply update a file across all the branches.

In this case it's a bashrc like file that specifies some environments variables. I have in the past updated the master branch version then rebased each branch. This has a sort of n+1 overhead, I'd like to avoid.

Answer 1

To extend fork0's comment, you need to combine:

• "How to iterate through all git branches using bash script"
• "git checkout specific files from another branch" (git checkout <branch_name> -- <paths>, from git checkout man page)

Ie:

#!/bin/bash
branches=()
eval "$(git for-each-ref --shell --format='branches+=(%(refname))' refs/heads/)"
for branch in "${branches[@]}"; do
  if [[ "${branch}" != "master" ]]; then
    git checkout ${branch}
    git checkout master -- yourFile        
  fi
done

(This is be adapted to your case, since here it always checkout the file from the master branch.)