How to find all uses of a blob in a git repo

Question

I have the SHA-1 object hash of a blob object in a (local) git repository. I need to find all uses in the form of commit-id, pathname and filename, e.g. generating all possible git show commands that would print the contents my blob:

git show <commit-id1>:foo/bar/baz.txt
git show <commit-id1>:README.txt
git show <commit-id2>:foo/quux.txt

Answer 1

I can use git log to find all commits I care about, and then use git ls-tree -r to find all the blobs in a commit, and then use Perl to keep only the blobs I'm interested in:

for COMMITID in `git log --pretty=format:%H`; do
  git ls-tree -r "$COMMITID" | perl -we '
      use integer; use strict; my $commitid = $ARGV[0]; my $f;
      die if !open($f, "<", "blobid.lst");
      my %h = map { s@\s.*@@s; $_ ? ($_=>1) : () } <$f>;
      while (<STDIN>) {
        die "bad: $_\n" if !s@^\S+\sblob\s([0-9a-f]{40})\t@@;
        my $blobid=$1;
        chomp;
        print "git show \x27$commitid:$_\x27\n" if $h{$blobid} }' -- "$COMMITID"
done

The list of the blob IDs I'm interested in are stored in the file blobid.lst, one ID per line.