I'll create a short todo to track this task and then give step-by-step git commands (fish-friendly) for common scenarios: resolving merge conflicts by accepting incoming messages.po, replacing with versions from another branch, and verifying/committing the changes.

Starting (1/1) *Provide git steps to replace messages.po files*

Below are clear, fish-shell–compatible recipes for the different situations you might be in. Pick the one that matches your case.

Safety first (recommended)
- Make a quick branch backup so you can undo if something goes wrong:
```fish
git branch backup-messages-po-(date +%Y%m%d%H%M%S)
```

A) You're in a merge (or rebase) conflict and want to accept the incoming branch's (theirs) version of every messages.po
- This accepts the "incoming" side for any conflicted messages.po files, stages them, and lets you continue.

1. List conflicted messages.po (preview):
```fish
git ls-files -u | awk '{print $4}' | sort -u | grep 'messages.po' || echo 'No conflicted messages.po'
```

2. Checkout the incoming/theirs version for each such file and stage them:
```fish
for f in (git ls-files -u | awk '{print $4}' | sort -u | grep 'messages.po')
    git checkout --theirs -- $f
    git add $f
end
```

3. Continue the merge/rebase:
- If you were merging:
```fish
git commit -m "Resolve conflicts: accept incoming messages.po"
```
- If you were rebasing:
```fish
git rebase --continue
```

B) You want to replace all local `messages.po` files with the versions from another branch (for example `upstream/main`)
- This is useful when you want to overwrite your workspace copies with the ones from a branch/commit.

1. Preview which files will be replaced:
```fish
find . -name 'messages.po' -print
```

2. Replace them with the version from `upstream/main` and stage:
```fish
for f in (find . -name 'messages.po')
    git checkout upstream/main -- $f
    git add $f
end
```

3. Commit the replacements:
```fish
git commit -m "Replace messages.po with versions from upstream/main"
```

C) Replace with files from a specific commit or tag
- Replace from commit SHA `abc1234`:
```fish
for f in (find . -name 'messages.po')
    git checkout abc1234 -- $f
    git add $f
end
git commit -m "Replace messages.po with versions from abc1234"
```

D) If you want to accept the remote side during a `git pull` merge conflict in one command
- (Linux GNU xargs version) — runs only if there are conflicting files:
```fish
git ls-files -u | awk '{print $4}' | sort -u | grep 'messages.po' | xargs -r -I{} sh -c 'git checkout --theirs -- "{}" && git add "{}"'
git commit -m "Accept incoming messages.po"
```
(Note: fish doesn't change how xargs behaves; use the `for` loop above if you prefer pure-fish syntax.)

Verification
- Show the diff (staged vs HEAD):
```fish
git diff --staged --name-only | grep 'messages.po' || echo 'No staged messages.po'
git diff --staged path/to/some/messages.po | less
```
- Or list all modified `messages.po` files:
```fish
git status --porcelain | grep 'messages.po' || echo 'No changes to messages.po'
```

Notes & gotchas
- --theirs applies to the branch you are merging in (the incoming changes). During conflicts, "ours" is your current branch.
- If no files match a pattern, some xargs implementations will error; the fish `for` loop approach is robust.
- Always make a backup branch before mass-replacing files if you might want to revert.
- If you use `git checkout <branch> -- <file>` note that modern Git also offers `git restore --source=<branch> -- <file>`; both work. Example:
```fish
for f in (find . -name 'messages.po')
    git restore --source=upstream/main -- $f
    git add $f
end
git commit -m "Restore messages.po from upstream/main"
```

If you tell me which exact situation you’re in (merge conflict, you want files from a branch, a specific commit, or from a tarball/patch), I can produce the exact commands tailored to that case and, if you want, a one-liner script to run.