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wrapper script for disc_id

I wrote a little wrapper script for disc_id tonight, available here. disc_id is a little binary that ships with libdvdread, or at least, it used to in older versions.

I use disc_id to give me a unique 32-character string of a DVD, so I have an identifier to track them by in my database of DVDs.

I don’t know if it’s just me or not, but my DVD drives have issues trying to poll the devices. Once I insert a disc, it will take a few seconds for it to register completely so I can access it. However, binaries that access it will think it’s ready to respond sooner than it is able, and will die unexpectedly. So what I needed was a way to get the disc id and not worry about whether or not the drive has finished registering or not.

I just call my little script dvd_id and it is simply a small wrapper that checks the exit code of the disc_id binary. If it doesn’t work the first time, it sleeps for one second and tries again, then repeats the process until it gets a successful exit code of zero.

That’s it. Pretty simple, but like all little scripts, you really tend to depend on them.
#!/bin/bash
EXIT_CODE=1
DEVICE=$1
if [[ -z $DEVICE ]]; then
DEVICE=/dev/dvd
fi

if [[ ! -b $DEVICE ]]; then
echo "Device $DEVICE doesn't exist" >&2
exit 1
fi

while [[ $EXIT_CODE != 0 ]]; do
/usr/local/bin/disc_id $DEVICE 2> /dev/null
EXIT_CODE=$?

if [[ $EXIT_CODE != 0 ]]; then
sleep 1
fi
done