How To See Index File Checksum?

Jon Forrest· Aug 17, 2025, 01:32 UTC · lore

I know how to see the checksums of the files in an index file. But, I can't find a git command that shows the checksum at the end of an index file.

Any ideas?

Cordially, Jon Forrest

Jeff King· Aug 17, 2025, 01:50 UTC · re: Jon Forrest · lore

Re: How To See Index File Checksum?

On Sat, Aug 16, 2025 at 06:32:30PM -0700, Jon Forrest wrote:

> I know how to see the checksums of the files in an index
> file. But, I can't find a git command that shows the
> checksum at the end of an index file.

I don't think that there's a command to do so (likewise for other checksum'd files like pack idx, etc). We'd usually check those during fsck but I don't know of any specific command to print them. I'd usually do something like:

   fn=.git/index
   size=$(stat --format=%s $fn)
   # offset of hash; use 32 in a sha256 repo!
   hash=$((size - 20))
   # the computed hash
   dd if=$fn bs=1 count=$hash | sha1sum
   # what the file records
   dd if=$fn bs=1 skip=$hash | od -A none -t x1 | tr -d ' \n'

Which admittedly is kind of horrible, but this isn't generally needed much outside of debugging.

-Peff