[Monotone-devel] Calling the shell from a hook

[William Uther]

Hi,
  I'm just playing with monotone to see if I want to do some  
projects with it.  Is there a way to get the output of a another  
process from within one of the lua hooks?

Background:

I use a Mac as my main machine, and it can store passwords in a  
'keychain' for me - like the ssh-agent for those who are familiar  
with that.  You can then use the shell to grab them:

% more bin/getPassword
#! /bin/sh

security find-generic-password -ga $1 2>&1 > /dev/null | sed -r -e 's/ 
password:
\"(.*)\"/\1/'

(see http://macromates.com/blog/archives/2006/04/17/keychain-access- 
from-shell/ for more info)

I've been trying to stick this into my monotone get_passphrase()  
hook, but this is my first time with lua.

I was hoping something like this would work:

function get_passphrase(keypair_id)
    pass = execute("/Users/willu/bin/getPassword", "monotoneKey")
    print("finished executing")
    print(pass)
    return pass
end

but that just prints the password on stdout before returning 0... not  
what I want.  It seems that some other people have managed to get  
data into monotone hooks using temporary files, but I'd really rather  
not save a cleartext copy of the password to the filesystem if I can  
help it (although I may have to - luckily I can use a unique password  
here).

I thought I'd first ask if there was a simple, and secure, way to get  
stdout from another process in Lua.

Any thoughts?

Will            :-}

P.S.  The other VCS I'm considering for this project is Mercurial.   
What do people here think are Monotone's main advantages, and  
disadvantages if you're willing to say, over Mercurial?

I've looked at Monotone before and it seems to have a healthy respect  
for data, which is nice.  Mercurial seems to be being chosen by a  
number of high-profile projects at the moment though.