I was wondering how to use a cron job to unzip a file and then eliminate the cron job so it doesn't repeatedly unzip the file once the original job is done?
crond is normally used for a repetive process, sounds like you should be using another method to acomplish what you want, give more details maybe there is another way.
if [ -e /myfile ]; then tar zxvf /myfile.tar.gz -C/outdir ; rm /myfile.tar.gz ; fi
If you're file exists it will extract it and then delete it to a give dir.
Don't know if you can implement this line directly in the crontab, else create this file in /root/fileunzip.sh or something and then add it to the cron