Re: [PATCH] Enable git rev-list to parse --quiet

From: Johannes Schindelin <johannes.schindelin@gmx.de>
Date: Jul 18, 2008, 10:50 UTC
Message-ID: <alpine.DEB.1.00.0807181246590.3932@eeepc-johanness>
In-Reply-To: <20080718092001.GD16102@mail.local.tull.net>

Hi,

On Fri, 18 Jul 2008, Nick Andrew wrote:

Show 11 quoted lines

> I want to automatically (e.g. in crontab) update a git repo to the 
> latest HEAD from a remote branch ... but with the possibility that the 
> local repo has local changes, and I want no chance of merge failure. In 
> other words, "git fetch remote; git merge origin/master" and only do the 
> merge if it's a fast-forward. If there are any local commits, or local 
> uncommitted changes, then leave the local working tree alone.
> 
> So my idea was to use "git rev-list --quiet master ^origin/master" and 
> check the exit code; if zero do "git merge origin/master". Without a 
> working "--quiet" nor exit code I can pipe the output to "wc -l" but is 
> there a more efficient/reliable way to implement the requirement?

Yes. Check if "$(git rev-parse master)" is different from "$(git rev-parse origin/master)" (to avoid unnecessary merging), and then that "$(git merge-base master origin/master)" is equal to "$(git rev-parse master)".

Note: this is plumbing, meant for scripting (which is exactly your 
scenario).  Do not teach this to new Git users.

Ciao, Dscho