I can use git archive to create an archive of files present at a particular commit. This is useful, I find, for sending everything to a collaborator, where there's no need to include the git history.
Now I want to know what was the commit ID at the time the archive was made.
The Git documentation says that when creating an archive like
git archive -o latest.zip HEAD
It's metadata stored in the zip file. Have you tried
unzip -Z latest.zip
UnZip 5.52 of 28 February 2005, by Info-ZIP. Maintained by C. Spieler. Send bug reports using http://www.info-zip.org/zip-bug.html; see README for details. Usage: unzip [-Z] [-opts[modifiers]] file[.zip] [list] [-x xlist] [-d exdir] Default action is to extract files in list, except those in xlist, to exdir; file[.zip] may be a wildcard. -Z => ZipInfo mode ("unzip -Z" for usage). -p extract files to pipe, no messages -l list files (short format) -f freshen existing files, create none -t test compressed archive data -u update files, create if necessary -z display archive comment -x exclude files that follow (in xlist) -d extract files into exdir modifiers: -q quiet mode (-qq => quieter) -n never overwrite existing files -a auto-convert any text files -o overwrite files WITHOUT prompting -aa treat ALL files as text -j junk paths (do not make directories) -v be verbose/print version info -C match filenames case-insensitively -L make (some) names lowercase -X restore UID/GID info -V retain VMS version numbers -K keep setuid/setgid/tacky permissions -M pipe through "more" pager Examples (see unzip.txt for more info): unzip data1 -x joe => extract all files except joe from zipfile data1.zip unzip -p foo | more => send contents of foo.zip via pipe into program more unzip -fo foo ReadMe => quietly replace existing ReadMe if archive file newer