Part of my application deployment pipeline on AWS includes a bash script that updates the hosts CRON file, in addition to running a ruby install as the user
sudo -u myuser bash << eof
echo 'running bundle install'
/home/myuser/.rvm/gems/ruby-2.4.1/wrappers/bundle install
echo 'install cron tasks'
(crontab -l 2>/dev/null; echo "TZ=America/Los_Angeles")| crontab -
(crontab -l 2>/dev/null; echo "CRON_TZ=America/Los_Angeles")| crontab -
(crontab -l 2>/dev/null; echo "00 13 * * * /bin/bash /var/www/application/bin/daily-notifications.sh")| crontab -
crontab -l
eof
unfortunately In order to update my AMI image I need to first manually go into my crontab file and erase the cron tasks first prior to taking a new image of the OS, because the code above is "appends" each line to the end of the existing file
is it possible in the bash script above to purge the cron tasks programmatically?
>Solution :
Yes, per the crontab manpage:
SYNOPSIS
crontab [ -u user ] file
crontab [ -u user ] [ -i ] { -e | -l | -r }
DESCRIPTION
[...]
The -r option causes the current crontab to be removed.
So you would use the command crontab -r