Naming commits

See git-rev-parse, gitrevisions, git-name-rev, git-describe, git-reflog

• To inspect your repository (and in scripts)

  $ pwd
  /home/marc/bash/lib
  $ git rev-parse  --is-inside-git-dir
  false
  $ git rev-parse  --is-inside-work-tree
  true
  $ git rev-parse --git-dir
  /shared/home/marc/bash/.git
  $ git rev-parse --show-cdup
  ../
  $ git rev-parse --show-prefix
  lib/
  

• translating symbolic <-> sha

  $ git rev-parse --symbolic-full-name HEAD
  refs/heads/master
  $ git symbolic-ref HEAD
  refs/heads/master
  $ git name-rev --name-only HEAD
  master
  $ git rev-parse  HEAD~3
  25f4b1d58e20f2026a36d80073654f52b055537b
  $ git name-rev --name-only 25f4b1d58e20
  master~3
  

• find the hash of some file

  • Look at Pro Git: Git Objects for details.
    • Discussion by Linus Torvald

  git hash-object <file>
  cat <file> | git hash-object --stdin
  (/usr/bin/stat  --printf "blob %s\0" calculette.c; cat calculette.c) | sha1sum
  

• to see remotes

  $ git remote
  lighttpd
  nx_server
  ssh_server
  ....
  $ git rev-parse  --symbolic --remotes
  lighttpd/master
  nx_server/distribution
  nx_server/kernoel
  nx_server/master
  ssh_server/distribution
  ssh_server/kernoel
  ssh_server/master
  ssh_server/tubuntu
  ....
  

• remote details

  $ git remote show ssh_server
  * remote ssh_server
    URL: ../ssh_server
    Tracked remote branches
    kernoel master tubuntu
    $ git config --get-regexp remote\\.ssh_server\\..\*
    remote.ssh_server.url ../ssh_server
    remote.ssh_server.fetch +refs/heads/*:refs/remotes/ssh_server/*
  

• version/most recent tag

  $ git describe HEAD
  init-1.0-29-gcb97cd9
  $ git name-rev --name-only cb97cd9
  master
  $ git describe HEAD~14
  init-1.0-15-g84aeca4
  $ git name-rev --name-only 84aeca4
  master~14
  $ git describe HEAD~29
  init-1.0
  $ git describe --long HEAD~29
  init-1.0-0-ge23c217
  

• past tips of branches

  We use the reflog, be careful that the reflog is local to your repository, and is pruned by git reflog expire or by git gc HEAD@{25} is the 25th older head of branch, this is not always the same than HEAD~25 which is the 25th ancestor of the actual head.

  $ git name-rev HEAD@{25}
  HEAD@{25} b3distrib~11
  $ git rev-parse HEAD@{25}
  2518dd006de12f8357e9694bf51a27bbd5bb5c7a
  $ git rev-parse HEAD~11
  2518dd006de12f8357e9694bf51a27bbd5bb5c7a
  $ git name-rev 2518dd0
  2518dd0 b3distrib~11
  $ git rev-parse HEAD@{18}
  0c4c8c0ea9ab54b92a2a6d2fed51d19c50cd3d76
  $ git name-rev HEAD@{18}
  HEAD@{18} undefined
  $ git rev-parse HEAD@{14}~4
  0c4c8c0ea9ab54b92a2a6d2fed51d19c50cd3d76
  $ git rev-parse HEAD@{13}~5
  24c85381f6d7420366e7a5e305c544a44f34fb0f
  git log -1 -g --oneline HEAD@{13}
  a1b9b5c HEAD@{13}: checkout: moving from b3distrib to a1b9b5c
  

  In the previous example The 13th ancestor from the HEAD is a checkout at the beginning of a rebase so HEAD@{14} is now dangling, and HEAD@{18} the fourth predecessor (HEAD@{14}~4) of HEAD@{14} is unreachable from a ref.

  Nevertheless HEAD@{25} has been rebased as HEAD~11 and can be reached.