Cron Jobs in Linux Crontab — Step-by-Step Tutorial

Every Linux distribution ships with cron, the daemon that runs scheduled commands in the background. This tutorial walks through creating, listing, and removing crontab entries, plus the environment quirks that catch almost every developer the first time they move a script from their terminal into cron.

Step 1: Open your crontab with crontab -e

Each user on the system has their own crontab. To edit yours:

$ crontab -e

# first time you run this, it may ask which editor to use:
# 1. /bin/nano   <---- easiest for beginners
# 2. /usr/bin/vim.basic
# choose 1 and press Enter

This opens an empty (or existing) crontab file. Every non-comment line is one scheduled job in the format minute hour day month weekday command.

Step 2: Add your first job

# Run a backup script every day at 2:30 AM
30 2 * * * /home/deploy/scripts/backup.sh

# Save and exit:
#   nano: Ctrl+O, Enter, then Ctrl+X
#   vim:  Esc, then :wq, Enter

After saving, cron reloads the crontab automatically — no need to restart any service. Verify it was saved with crontab -l (list) at any time.

Step 3: Redirect output so you can actually see what happened

By default, cron tries to email job output to you, but most servers don't have local mail configured, so output silently disappears. Always redirect explicitly:

# Append both stdout and stderr to a log file
30 2 * * * /home/deploy/scripts/backup.sh >> /home/deploy/logs/backup.log 2>&1

# Discard output entirely (not recommended — you lose error visibility)
30 2 * * * /home/deploy/scripts/backup.sh > /dev/null 2>&1

Step 4: Fix the #1 gotcha — PATH and environment variables

Cron does not load your .bashrc, .bash_profile, or .profile. It runs with a bare-minimum environment, so a script that calls node, python3, or npm by name — and works fine in your terminal — often fails silently or with "command not found" under cron.

• Use full absolute paths in crontab commands: /usr/bin/node instead of node.
• Or set PATH explicitly at the top of the crontab file: PATH=/usr/local/bin:/usr/bin:/bin.
• Or source your environment at the top of the script itself, e.g. source /home/deploy/.nvm/nvm.sh before calling node.
• Check exactly what environment cron gives you by scheduling * * * * * env > /tmp/cron-env.txt once, then deleting the entry.

# Top of crontab — set PATH and any env vars all jobs need
PATH=/usr/local/bin:/usr/local/sbin:/usr/bin:/bin
NODE_ENV=production

*/10 * * * * /usr/bin/node /home/deploy/app/sync.js

Step 5: Other crontab commands you'll need

• crontab -l — list the current user's crontab entries.
• crontab -r — remove the entire crontab for the current user (no confirmation — be careful).
• sudo crontab -u username -e — edit another user's crontab (requires root).
• /etc/crontab and /etc/cron.d/ — system-wide crontabs; these require an extra "user" field between the schedule and the command.
• systemctl status cron (Debian/Ubuntu) or systemctl status crond (RHEL/CentOS) — confirm the cron daemon itself is running.

Frequently Asked Questions