Thanks for the pointers. With a little cleanup I got a script that lists the PPAs, but not any other repository:

listppas script:

#! /bin/sh 



# listppas Script to get all the PPAs installed on a system ready to share for

# reininstall



for APT in `find /etc/apt/ -name *.list`; do

    grep -o "^deb http://ppa.launchpad.net/[a-z0-9-]+/[a-z0-9-]+" $APT 

            | while read ENTRY ; do

        USER=`echo $ENTRY | cut -d/ -f4`

        PPA=`echo $ENTRY | cut -d/ -f5`

        echo sudo apt-add-repository ppa:$USER/$PPA

    done

done

When you call it with listppas > installppas.sh you get an installppas.sh script you can copy onto a new machine to reinstall all PPAs.

Next stop: do that for the other repositories:

Final listppas script:

#! /bin/sh



# Script to get all the PPAs which are installed on a system



for APT in `find /etc/apt/ -name *.list`; do

    grep -Po "(?<=^debs).*?(?=#|$)" $APT | while read ENTRY ; do

        HOST=`echo $ENTRY | cut -d/ -f3`

        USER=`echo $ENTRY | cut -d/ -f4`

        PPA=`echo $ENTRY | cut -d/ -f5`

        #echo sudo apt-add-repository ppa:$USER/$PPA

        if [ "ppa.launchpad.net" = "$HOST" ]; then

            echo sudo apt-add-repository ppa:$USER/$PPA

        else

            echo sudo apt-add-repository '${ENTRY}'

        fi

    done

done

This should do the trick. Use it as listppas > installppas.sh on the source machine, then run the contents of installppas.sh on the destination machine.

I needed a question on superuser to figure out the correct regex.