Command:
$ crontab -l
Result:
*/30 * * * * perl -le 'sleep rand 360' && csv="list.csv"; wc=$[`wc -l < $csv` - 1]; rand=$[`./rand_nobias.sh $wc`]; head -$[$[$rand \% $wc] + 2] $csv | tail -1 | /usr/local/bin/gawk -f formatcsv.awk | ruby tweet.rb