I have a git repo of configuration files segregated by branches, e.g.:
refs/heads/branch1, file - settings.properties
refs/heads/branch2, file - settings.properties
etc.
I'm trying to grep certain property of every each of the settings.properties file in every each of the repository:
git for-each-ref refs/heads --shell --format=‘%(refname:short)’ | xargs -n1 git checkout | cat settings.properties | grep ‘host.name’
The first command gives me the list of my branches, the second one checks me out to every branch one after another and I expect 3rd command cat the file and 4th to grep certain property. First 2 commands work just fine but if I run the whole thing it just greps host.name only for the first branch.
I'm obviously missing something essential about the pipelines. I know I can write it as a shell script and do all this in a loop, but I would like to keep the 'pipeline' approach, because I may often need to cat different files and grep different properties and wouldn't want to deal with passing parameters into the script
You don't need to check out each branch to get the information about that file. You can instead use git cat-file to show the contents of the file on that branch instead.
So you could do something a little like this (untested):
git for-each-ref refs/heads --shell --format='%(refname:short)' | \
xargs -n1 -I{} git cat-file blob {}:settings.properties | grep 'host.name'
Or if you wanted it to be even shorter, you could just use git grep directly:
git for-each-ref refs/heads --shell --format='%(refname:short)' | \
xargs -n1 -I{} git --no-pager grep host.name {}:settings.properties