Debian: Holding packages you build from source, and rebuilding them easily (Shallow Thoughts)

Akkana's Musings on Open Source Computing and Technology, Science, and Nature.

Sat, 26 Mar 2016

Debian: Holding packages you build from source, and rebuilding them easily

Recently I wrote about building the Debian hexchat package to correct a key binding bug.

I built my own version of the hexchat packages, then installed the ones I needed:

dpkg -i hexchat_2.10.2-1_i386.deb hexchat-common_2.10.2-1_all.deb hexchat-python_2.10.2-1_i386.deb hexchat-perl_2.10.2-1_i386.deb

That's fine, but of course, a few days later Debian had an update to the hexchat package that wiped out my changes.

The solution to that is to hold the packages so they won't be overwritten on the next apt-get upgrade:

aptitude hold hexchat hexchat-common hexchat-perl hexchat-python

If you forget which packages you've held, you can find out with aptitude:

aptitude search '~ahold'

Simplifying the rebuilding process

But now I wanted an easier way to build the package. I didn't want to have to search for my old blog post and paste the lines one by one every time there was an update -- then I'd get lazy and never update the package, and I'd never get security fixes.

I solved that with a zsh function:

newhexchat() {
    # Can't set errreturn yet, because that will cause mv and rm
    # (even with -f) to exit if there's nothing to remove.
    cd ~/outsrc/hexchat
    echo "Removing what was in old previously"
    rm -rf old
    echo "Moving everything here to old/"
    mkdir old
    mv *.* old/

    # Make sure this exits on errors from here on!
    setopt localoptions errreturn

    echo "Getting source ..."
    apt-get source hexchat
    cd hexchat-2*
    echo "Patching ..."
    patch -p0 < ~/outsrc/hexchat-2.10.2.patch
    echo "Building ..."
    debuild -b -uc -us
    echo
    echo 'Installing' ../hexchat{,-python,-perl}_2*.deb
    sudo dpkg -i ../hexchat{,-python,-perl}_2*.deb
}

Now I can type newhexchat and pull a new version of the source, build it, and install the new packages.

How do you know if you need to rebuild?

One more thing. How can I find out when there's a new version of hexchat, so I know I need to build new source in case there's a security fix?

One way is the Debian Package Tracking System. You can subscribe to a package and get emails when a new version is released. There's supposed to be a package tracker web interface, e.g. package tracker: hexchat with a form you can fill out to subscribe to updates -- but for some packages, including hexchat, there's no form. Clicking on the link for the new package tracker goes to a similar page that also doesn't have a form.

So I guess the only option is to subscribe by email. Send mail to pts@qa.debian.org containing this line:

subscribe hexchat [your-email-address]
You'll get a reply asking for confirmation.

This may turn out to generate too much mail: I've only just subscribed, so I don't know yet. There are supposedly keywords you can use to limit the subscription, such as upload-binary and upload-source, but the instructions aren't at all clear on how to include them in your subscription mail -- you say keyword, or keyword your-email, so where do you put the actual keywords you want to accept? They offer no examples.

Use apt to check whether your version is current

If you can't get the email interface to work or suspect it'll be too much email, you can use apt to check whether the current version in the repository is higher than the one you're running:

apt-cache policy hexchat

You might want to automate that, to make it easy to check on every package you've held to see if there's a new version. Here's a little shell function to do that:

# Check on status of all held packages:
check_holds() {
    for pkg in $( aptitude search '~ahold' | awk '{print $2}' ); do
        policy=$(apt-cache policy $pkg)
        installed=$(echo $policy | grep Installed: | awk '{print $2}' )
        candidate=$(echo $policy | grep Candidate: | awk '{print $2}' )
        if [[ "$installed" == "$candidate" ]]; then
            echo $pkg : nothing new
        else
            echo $pkg : new version $candidate available
        fi
    done
}

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[ 11:11 Mar 26, 2016    More linux | permalink to this entry | comments ]
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