sync-available has a syntax error and possibly a bashism

Binary package hint: dctrl-tools

There's a syntax error in sync-available:

apollock@frustration:~$ sudo sync-available
[: 41: Illegal number:
Merging available database in /tmp/apt-available.WK6905...done.
Replacing available packages info, using /tmp/apt-available.WK6905.
Information about 24871 package(s) was updated.

apollock@frustration:~$ sudo sh -x /usr/sbin/sync-available
+ set -e
+ aptcache=/usr/bin/apt-cache
+ [ 0 -ge 1 ]
+ [ -ne 0 ]
[: 1: Illegal number:
+ [ ! -x /usr/bin/apt-cache ]
+ mktemp -t apt-available.XXXXXX
+ tf=/tmp/apt-available.Uh6930
+ echo -n Merging available database in /tmp/apt-available.Uh6930...
Merging available database in /tmp/apt-available.Uh6930...+ /usr/bin/apt-cache dumpavail
+ echo done.
done.
+ dpkg --update-avail /tmp/apt-available.Uh6930
Replacing available packages info, using /tmp/apt-available.Uh6930.
Information about 24871 package(s) was updated.
+ rm /tmp/apt-available.Uh6930

I think it's this part:

if [ "$EUID" -ne "0" ]
then
    echo "$0: root privileges are required"
    exit 1
fi

If you're going to compare these as strings, you should use the == string comparison operator, not the -ne numeric comparison operator.

So your choices are:

if [ -n "$EUID" ] && [ $EUID -ne 0 ]

or

if [ "$EUID" == "0" ]

That said, $EUID seems to be a bash-provided variable, according to the bash man page, but I can't see any mention of dash providing it. That'll be why this syntax error is being exposed in the first place.