文章 - 如何查看 Linux Cron Jobs ？

Crontab Schedule

Cron 这个名字来源于希腊单词 Chronos，用来表示时间。它是 Linux 系统的一个守护进程，用于按指定的时间间隔自动执行命令或脚本。本文将介绍如何查看 Linux 中运行的 Cron Jobs，希望对你有用。

List Current User Cron Jobs

列出当前用户的所有 Cron Jobs，使用如下命令：

crontab –l

list cron jobs of current user

用户的 cron jobs 通常位于 /var/spool/cron/crontabs 目录下，存储在以用户名命名的单独文件下。

List Other User Cron Jobs

root 或 sudo 用户也可以查看其他用户的 Cron Jobs，使用如下命令：

sudo crontab –u username –l

List System Cron Jobs

以 root 或 sudo 帐户可以查看系统的 Cron Jobs，使用如下命令：

less /etc/crontab

输出如下：

# /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

# Example of job definition:
# .---------------- minute (0 - 59)
# |  .------------- hour (0 - 23)
# |  |  .---------- day of month (1 - 31)
# |  |  |  .------- month (1 - 12) OR jan,feb,mar,apr ...
# |  |  |  |  .---- day of week (0 - 6) (Sunday=0 or 7) OR sun,mon,tue,wed,thu,fri,sat
# |  |  |  |  |
# *  *  *  *  * user-name command to be executed
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 )

List Hourly Cron Jobs

ls -la /etc/cron.hourly

输出如下：

total 20
drwxr-xr-x   2 root root  4096 Apr 23  2020 .
drwxr-xr-x 142 root root 12288 Jan 19 15:21 ..
-rw-r--r--   1 root root   102 Feb 14  2020 .placeholder

List Daily Cron Jobs

ls -la /etc/cron.daily

输出如下：

total 72
drwxr-xr-x   2 root root  4096 Dec 28 15:28 .
drwxr-xr-x 142 root root 12288 Jan 19 15:21 ..
-rwxr-xr-x   1 root root   311 Jul 16  2019 0anacron
-rwxr-xr-x   1 root root   539 Apr 13  2020 apache2
-rwxr-xr-x   1 root root   376 Dec  5  2019 apport
-rwxr-xr-x   1 root root  1478 Apr  9  2020 apt-compat
-rwxr-xr-x   1 root root   355 Dec 29  2017 bsdmainutils
-rwxr-xr-x   1 root root   384 Nov 19  2019 cracklib-runtime
-rwxr-xr-x   1 root root  1187 Sep  6  2019 dpkg
-rwxr-xr-x   1 root root   377 Jan 21  2019 logrotate
-rwxr-xr-x   1 root root  1123 Feb 25  2020 man-db
-rw-r--r--   1 root root   102 Feb 14  2020 .placeholder
-rwxr-xr-x   1 root root  4574 Jul 18  2019 popularity-contest
-rwxr-xr-x   1 root root   383 Jan  6  2020 samba
-rwxr-xr-x   1 root root   214 Apr  2  2020 update-notifier-common

List Weekly Cron Jobs

ls -la /etc/cron.weekly

输出如下：

total 32
drwxr-xr-x   2 root root  4096 Apr 23  2020 .
drwxr-xr-x 142 root root 12288 Jan 19 15:21 ..
-rwxr-xr-x   1 root root   312 Jul 16  2019 0anacron
-rwxr-xr-x   1 root root   813 Feb 25  2020 man-db
-rw-r--r--   1 root root   102 Feb 14  2020 .placeholder
-rwxr-xr-x   1 root root   211 Apr  2  2020 update-notifier-common

List Montly Cron Jobs

ls -la /etc/cron.monthly

输出如下：

total 24
drwxr-xr-x   2 root root  4096 Apr 23  2020 .
drwxr-xr-x 142 root root 12288 Jan 19 15:21 ..
-rwxr-xr-x   1 root root   313 Jul 16  2019 0anacron
-rw-r--r--   1 root root   102 Feb 14  2020 .placeholder

List Current User Cron Jobs

List Other User Cron Jobs

List System Cron Jobs

List Hourly Cron Jobs

List Daily Cron Jobs

List Weekly Cron Jobs

List Montly Cron Jobs

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