Introduction
Cron is a Linux utility for scheduling scripts and commands. This guide will show you several options to view current cron jobs scheduled in the crontab list.
Prerequisites
- A user account with sudo privileges
- Access to a terminal window / command line (Ctrl+Alt+T, Ctrl+Alt+F2)
Listing Cron Jobs in Linux
How to List all Active Cron Jobs Running
To list all scheduled cron jobs for the current user, enter:
crontab –l
Cron jobs are typically located in the spool directories. They are stored in tables called crontabs. You can find them in /var/spool/cron/crontabs. The tables contain the cron jobs for all users, except the root user.
The root user can use the crontab for the whole system.
To display contents of the root user’s crontab, use the less command:
less /etc/crontabThe system returns an output like the following:
# /etc/crontab: system-wide crontab
# Unlike any other crontab you don't have to run the `crontab'
# command to install the new version when you edit this file
# and files in /etc/cron.d. These files also have username fields,
# that none of the other crontabs do.
SHELL=/bin/sh
PATH=/usr/local/sbin:/usr/local/bin:/sbin:/bin:/usr/sbin:/usr/bin
# m h dom mon dow user command
17 * * * * root cd / && run-parts --report /etc/cron.hourly
25 6 * * * root test -x /usr/sbin/anacron || ( cd / && run-parts --report /etc/cron.daily )
47 6 * * 7 root test -x /usr/sbin/anacron || ( cd / && run-parts --report /etc/cron.weekly )
52 6 1 * * root test -x /usr/sbin/anacron || ( cd / && run-parts --report /etc/cron.monthly )The /etc/crontab file can be edited using a text editor like nano:
sudo nano /etc/crontabIn RedHat-based systems, this file is located at /etc/cron.d.
The /etc/ directory has additional cron subdirectories to organize hourly, daily, weekly, and monthly tasks. The ls (list) command displays files and directories. Use the –la option to list all entries in long format.
View Cron Jobs by User
To list cron jobs that belong to a specific user, run the following command:
sudo crontab –u username –lReplace username with the actual username you’re viewing.
How to List Hourly Cron Jobs
To list hourly cron jobs enter the following in the terminal window:
ls –la /etc/cron.hourlyThe output should appear similar to this:
How to List Daily Cron Jobs
To list daily cron jobs, enter the command:
ls –la /etc/cron.dailyThe results will look similar to the following output:
How to Display Weekly Cron Jobs
To display weekly cron jobs:
ls –la /etc/cron.weeklyThe results will look something like the following:
total 28
drwxr-xr-x 2 root root 4096 Apr 24 20:46 .
drwxr-xr-x 96 root root 4096 May 19 17:12 ..
-rw-r--r-- 1 root root 102 Feb 9 2013 .placeholder
-rwxr-xr-x 1 root root 730 Feb 23 2014 apt-xapian-index
-rwxr-xr-x 1 root root 427 Apr 16 2014 fstrim
-rwxr-xr-x 1 root root 771 Sep 23 2014 man-db
-rwxr-xr-x 1 root root 211 Mar 27 2017 update-notifier-commonHow to List Monthly Cron Jobs
To display monthly cron jobs use the ls command in this format:
ls –la /etc/cron.monthlyThe results appear as:
total 12
drwxr-xr-x 2 root root 4096 Apr 24 20:44 .
drwxr-xr-x 96 root root 4096 May 19 17:12 ..
-rw-r--r-- 1 root root 102 Feb 9 2013 .placeholderView Software Specific Cron Jobs
To view software specefic cron tasks, start by viewing a list of cron tasks:
cd /etc/cron/daily
ls –lUse the cat command to display the contents of update-notifier-common:
cat update–notifier–commonThe results will look similar to:
#!/bin/sh
set -e
[ -x /usr/lib/update-notifier/package-data-downloader ] || exit 0
# Try to rerun any package data downloads that failed at package install time.
/usr/lib/update-notifier/package-data-downloaderConclusion
Now you know how to navigate through the cron jobs on your machine. Cron is a helpful utility for scheduling tasks such as running a job at reboot. Use the commands from this guide to sort and display tasks scheduled through the cron tool.
