update-branches-with-empty-commits.hs

#!/usr/bin/env runhaskell

import System.Process ( readProcess )
import System.Environment ( getArgs )
import Control.Monad (forM_)

main :: IO ()
main = do
  branch <- head <$> getArgs
  let repos = [ "repo1"
              , "repo2"
              , "repo3" ] -- Replace with your own repo names
  forM_ repos (updateRepo branch)

-- Update the repo at `repo` with an empty commit on the branch `branch`
updateRepo :: String -> String -> IO String
updateRepo branch repo = do
  let path = repoPath repo
  _ <- runGit path ["checkout", "master"]
  _ <- runGit path ["pull", "--rebase"]
  _ <- switchToBranch path branch
  _ <- runGit path ["pull", "--rebase"]
  _ <- runGit path ["commit", "--allow-empty", "-m", "commit message"] -- Put your commit message here
  runGit path ["push", "-u", "origin", branch]

-- Get the path of the repo specified by `repo`
repoPath :: String -> String
repoPath repo = "/homedir/" <> repo -- Replace with your home directory, e.g., "/Users/me/projects/"

-- Switch to a branch in the repo at `path`. Creates the branch if it does not exist.
switchToBranch :: String -> String -> IO String
switchToBranch path branch = do
  branches <- getBranches path
  if branch `elem` branches then
    runGit path ["checkout", branch]
  else
    runGit path ["checkout", "-b", branch]

-- Get the branches of a repo at `path`
getBranches :: String -> IO [String]
getBranches path = fmap words (readProcess "git" ["-C", path, "branch"] "")

-- Run git with `args` in the working directory at `path`
runGit :: String -> [String] -> IO String
runGit path args =
  readProcess "git" (["-C", path] <> args) ""