Fix 'crontab: command not found'
'crontab: command not found' means the cron package isn't installed on the system. Install the cron (or cronie) package for your distribution, then enable and start the service. This is common on minimal server images and Docker base images.
Debian / Ubuntu
sudo apt update && sudo apt install -y cron, then sudo systemctl enable --now cron.
RHEL / CentOS / Fedora / Rocky
sudo yum install -y cronie (or dnf), then sudo systemctl enable --now crond.
Alpine (common in Docker)
apk add --no-cache busybox-suid enables crontab, or install dcron. Start it with crond.
Confirm it worked
Run which crontab — you should get a path like /usr/bin/crontab. Then crontab -l lists jobs (or says there are none), confirming the command is available.
FAQ
Why is crontab command not found?
The cron package isn't installed. Install it: apt install cron on Debian/Ubuntu, yum install cronie on RHEL/CentOS, busybox-suid or dcron on Alpine.
How do I install crontab on Ubuntu?
sudo apt update && sudo apt install -y cron, then sudo systemctl enable --now cron to start the service.
Why is crontab missing in my Docker container?
Minimal base images omit cron. On Alpine run apk add busybox-suid (or dcron); on Debian slim images apt install cron, then start crond/cron.