git show-branch -a complains that there are too many refs

Question

I want to use the below on a windows 10 machine to know the nearest parent of a git branch.

But I am not able to run it, please help.

#!/usr/bin/env zsh

git show-branch -a \
| grep '\*' \
| grep -v `git rev-parse --abbrev-ref HEAD` \
| head -n1 \
| sed 's/.*\[\(.*\)\].*/\1/' \
| sed 's/[\^~].*//'

# How it works:
# 1| Display a textual history of all commits.
# 2| Ancestors of the current commit are indicated
#    by a star. Filter out everything else.
# 3| Ignore all the commits in the current branch.
# 4| The first result will be the nearest ancestor branch.
#    Ignore the other results.
# 5| Branch names are displayed [in brackets]. Ignore 
#    everything outside the brackets, and the brackets.
# 6| Sometimes the branch name will include a ~2 or ^1 to
#    indicate how many commits are between the referenced
#    commit and the branch tip. We don't care. Ignore them.

I have taken the script form https://gist.github.com/joechrysler/6073741#file-who_is_my_mummy-sh

FYI, I have very limited Linux knowledge.

I don't want to use WSL or Cygwin

I have got the grep.exe and sed.exe and other exes from Linux utils.

Even If I run the below command in the windows command prompt, I get the below error

git show-branch -a | grep '\*'

Error:

warning: ignoring origin/branchname; cannot handle more than 26 refs

Edit:

I saved the above command in a file parent.sh and When I run it in Git Bash, It gives the below error. Am I missing anything here?

Answer 1

This has nothing to do with Linux or Windows, and not much to do with shells: you are running into a built in limit in the git show-branch command. The git show-branch command has an internal maximum of 26 "refs" (branch names plus remote-tracking names).¹ You have a large number of remote-tracking names—the names that start with origin/, such as origin/63747—and it's more than git show-branch can handle.

You could increase this limit by downloading the source for Git and building a new version of git show-branch that has a bigger limit in it, but that's a pretty big job even for an experienced C programmer (because it involves changing the way the bits work in show-branch, which gets its limit based on the number of flags used in internal commit objects; see the TODO in builtin/showbranch.c).

You might just need a different (more capable) script. Consider some of the other answers to this question: How to find the nearest parent of a Git branch

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¹Note that this limit used to be slightly larger (29, at the time some of the scripts in the above StackOverflow question were written).