Cronab log: how to record the output of my cron script

I created a backup.sh shell Script and add it to my crontab To execute it every day . How to verify backup cron Whether the script job runs successfully ？ Besides , my backup.sh shell There are several in the script echo sentence . When the script acts as cron When the job is performed , How to save the output of the script to the log file ？

Suppose you have backup.sh Add to your crontab in , As shown below , In order to execute it every morning .

$ crontab -e59 23 * * * /home/john/bin/backup.sh

To verify whether this job was successfully executed , Please check /var/log/cron file , This file contains all the information about the execution in the system cron Job information . You can see from the following output ,john Of cron The job has been successfully executed .

$ tail /var/log/cronOct  8 22:00:00 dev-db crond[18340]: (root) CMD (/bin/sh /home/root/bin/system_check &)Oct  8 23:00:00 dev-db crond[20348]: (oracle) CMD (/bin/sh /home/oracle/bin/cleanup.sh &)Oct  8 23:59:00 dev-db crond[20399]: (john) CMD (/bin/sh /home/john/bin/backup.sh &)

Cron The log contains the following information ：

• Time stamp - perform cron The date and time of the assignment
• Host name – The hostname of the server （ for example dev-db）
• cron Daemon name and PID. for example ,crond[20399]
• user name – Execute this cron User name of the job . for example , John .
• CMD – Everything after that is the real order executed at that time .

If backup.sh Any of them echo sentence , You may want to record them in a file . Usually , If backup.sh cron The script throws any output （ Including mistakes ）, You may want to record these outputs to a log file . So , Please amend crontab Entry and add output and error redirection , As shown below .

$ crontab -e59 23 * * * /home/john/bin/backup.sh > /home/john/logs/backup.log 2>&1

on top ：

• > /home/john/logs/backup.log It means that you will backup.sh The standard output of the script is redirected to backup.log file .
• 2>&1 Indicates a standard error (2>) Redirected to standard output (&1) Same file descriptor pointed to .
• therefore , Both standard output and errors will be redirected to /home/john/logs/backup.log