Question

This should be a very simple thing to have run, but for some reason it won’t work with my Mercurial repository. All I want is for the remote repo to automatically run hg update whenever someone pushes to it. So I have this in my .hg/hgrc file:

[hook]
changegroup = hg update

Simple, right? But for some reason, this never executes. I also tried writing a shell script that did this. .hg/hgrc looked like this:

[hooks]
changegroup = /home/marc/bin/hg-update

and hg-update looked like this:

#!/bin/sh
hg help >> /home/marc/works.txt;
hg update >> /home/marc/works.txt;
exit 0;

But again, this doesn’t update. The contents of hg help are written out to works.txt, but nothing is written out for hg update. Is there something obvious I’m missing here? This has been plaguing me for days and I just can’t seem to get it to work.

Update

Okay so again, using the -v switch on the command line from my workstation pushing to the remote repo doesn’t print any verbose messages even when I have those echo lines in .hg/hgrc. However, when I do a push from a clone of the repo on the same filesystem (I’m logged in via SSH), this is what I get:

bash-3.00$ hg -v push ../test-repo/
pushing to ../test-repo/
searching for changes
1 changesets found
running hook prechangegroup: echo "Remote repo is at `hg tip -q`"
echo "Remote repo wdir is at `hg parents -q`"
Remote repo is at 821:1f2656753c98
Remote repo wdir is at 821:1f2656753c98
adding changesets
adding manifests
adding file changes
added 1 changesets with 1 changes to 1 files
running hook changegroup: echo "Updating.... `hg update -v`"
echo "Remote repo is at `hg tip -q`"
echo "Remote repo wdir is at `hg parents -q`"
Updating.... resolving manifests
getting license.txt
1 files updated, 0 files merged, 0 files removed, 0 files unresolved
Remote repo is at 822:389a6c7276c6
Remote repo wdir is at 822:389a6c7276c6

So it works, but again only when I push from the same filesystem. It doesn’t work if I try pushing to the repo from another workstation over the network.

Answer 1

I spent some time researching this myself. I think the answer to problem is described concisely here:

Output has to be redirected to stderr (or /dev/null), because stdout
is used for the data stream.

Basically, you’re not redirecting to stderr, and hence polluting stdout.