CRON无法在Amazon EC2中工作？

Question

Another article describes that a way to test if cron is running is to create a crontab -e with this script:

* * * * * /usr/bin/uptime > /tmp/uptime

When i go check on the cron cat /tmp/uptime there is no result. The same goes with a test script with a direct path to php.

I'm running AWS running Amazon Linux.

I checked to see if cron was even running with chkconfig --list crond result:

crond           0:off   1:off   2:on    3:on    4:on    5:on    6:off

UPDATE (based on comments)

[ec2-user@ip-xxx-xxx ~]$ service crond status
crond (pid  2844) is running...
[ec2-user@ip-xxx-xxx ~]$ ps aux | grep crond
root      2844  0.0  0.2 121636  2572 ?        Ss   Sep04   0:01 crond
ec2-user  7904  0.0  0.2 110468  2096 pts/0    S+   22:46   0:00 grep --color=auto crond

Just to be safe I manually started cron with this command:

sudo service crond start

I've also tried sudo su and created instances both in ec2-user and root. Nothing seems to actually run the cron.

Does anyone have any suggestions? It seems that the docs on Cron elsewhere are several years old. Thanks in advance.

Reference:

Setting Up Cron in Amazon Linux AMI

Answer 1

have you check the cron daemon status ?

$ service crond status
crond (pid xxx) is running...
$ ps aux | grep crond
root      2533  0.0  0.1 119552  1784 ?        Ss   Apr04   1:57 crond
ec2-user 22203  0.0  0.2 110460  2084 pts/0    S+   09:37   0:00 grep --color=auto crond

then, if cron daemon seems not running you can start it

$ service crond start

Answer 2

Verify that procps package is installed (that package provides uptime command)

sudo yum install procps

Also verify that your cron job is saved

crontab -l

Answer 3

Do the following:

sudo service crond reload

or

sudo service crond restart

This could happen to VPS server, after you do the crontab modification, you might need to reload it in order for the modification to take place. In the worse case scenario, the crond restart will stop the service and start it again. Hope that helps.

Answer 4

     [ec2-user@ip-172-31-47-191 ~]$ sudo crontab -l
no crontab for root
[ec2-user@ip-172-31-47-191 ~]$ sudo crontab -e
no crontab for root - using an empty one
crontab: installing new crontab
[ec2-user@ip-172-31-47-191 ~]$ sudo crontab -l
* * * * * /usr/bin/uptime > /tmp/uptime

[ec2-user@ip-172-31-47-191 ~]$ /usr/bin/uptime
 23:05:09 up 284 days, 12:52,  1 user,  load average: 0.01, 0.02, 0.05
 [ec2-user@ip-172-31-47-191 ~]$ ls -l /tmp
total 4
drwx------. 2 oracle dba   6 Sep  7 11:03 mc-oracle
drwx------. 2 root   root  6 Sep  7 11:01 mc-root
-rw-r--r--. 1 root   root 71 Sep 14 23:05 uptime
 [ec2-user@ip-172-31-47-191 ~]$ more /tmp/uptime
 23:05:01 up 284 days, 12:52,  1 user,  load average: 0.01, 0.02, 0.05
 [ec2-user@ip-172-31-47-191 ~]$  service crond status
Redirecting to /bin/systemctl status  crond.service
● crond.service - Command Scheduler
   Loaded: loaded (/usr/lib/systemd/system/crond.service; enabled; vendor preset: enabled)
   Active: active (running) since Thu 2017-04-20 03:07:03 EDT; 4 months 26 days ago
 Main PID: 16998 (crond)
   CGroup: /system.slice/crond.service
           └─16998 /usr/sbin/crond -n

Warning: Journal has been rotated since unit was started. Log output is incomplete or unavailable.
[ec2-user@ip-172-31-47-191 ~]$ 191 ~]$

Answer 5

检查/ var / log / cron日志文件以验证您的命令是否正在运行。