What does git rev-parse do

Question

What does git rev-parse do   I have read the man page but it raised more questions than answers  Things like      Pick out and massage parameters   Massage  What does that mean   I m using as a resolver  to SHA1  of revision specifiers  like  git rev-parse HEAD    or  git rev-parse origin master   Is this the command   s purpose  If not  is even correct to use it to achieve this

User · Accepted Answer

git rev-parse is an ancillary plumbing command primarily used for manipulation   One common usage of git rev-parse is to print the SHA1 hashes given a revision specifier  In addition  it has various options to format this output such as --short for printing a shorter unique SHA1   There are other use cases as well  in scripts and other tools built on top of git  that I ve used for    --verify to verify that the specified object is a valid git object  --git-dir for displaying the abs relative path of the the  git directory  Checking if you re currently within a repository using --is-inside-git-dir or within a work-tree using --is-inside-work-tree Checking if the repo is a bare using --is-bare-repository Printing SHA1 hashes of branches  --branches   tags  --tags  and the refs can also be filtered based on the remote  using --remote  --parse-opt to normalize arguments in a script  kind of similar to getopt  and print an output string that can be used with eval   Massage just implies that it is possible to convert the info from one form into another i e  a transformation command  These are some quick examples I can think of    a branch or tag name into the commit s SHA1 it is pointing to so that it can be passed to a plumbing command which only accepts SHA1 values for the commit  a revision range A  B for git log or git diff into the equivalent arguments for the underlying plumbing command as B  A

User · Answer

git rev-parse Also works for getting the current branch name using the --abbrev-ref flag like  git rev-parse --abbrev-ref HEAD

User · Answer

Just to elaborate on the etymology of the command name rev-parse  Git consistently uses the term rev in plumbing commands as short for  revision  and generally meaning the 40-character SHA1 hash for a commit  The command rev-list for example prints a list of 40-char commit hashes for a branch or whatever   In this case the name might be expanded to parse-a-commitish-to-a-full-SHA1-hash  While the command has the several ancillary functions mentioned in Tuxdude s answer  its namesake appears to be the use case of transforming a user-friendly reference like a branch name or abbreviated hash into the unambiguous 40-character SHA1 hash most useful for many programming plumbing purposes   I know I was thinking it was  reverse-parse  something for quite a while before I figured it out and had the same trouble making sense of the terms  massaging  and  manipulation      Anyway  I find this  parse-to-a-revision  notion a satisfying way to think of it  and a reliable concept for bringing this command to mind when I need that sort of thing  Frequently in scripting Git you take a user-friendly commit reference as user input and generally want to get it resolved to a validated and unambiguous working reference as soon after receiving it as possible  Otherwise input translation and validation tends to proliferate through the script

[git] What does git rev-parse do?

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Examples related to git-rev-parse