Recently I have to use crontab to run a script at midnight (a Hadoop job in our office cluster to collect some tracking data). To follow the script’s log, I use tee to fork the log to some log file named with the date. But after the day I set the cronjob, I found nothing in the grafana neither of the HDFS, this means the job didn’t run.
I wrote the job command as follows:
# 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 0 1 * * * root bash /home/myname/collect/run.sh | tee /home/myname/collect/log/$(date +%s).log
What do you think of this script? Is it really OK to run?
vim shows me a different color of the character
%. Firstly I didn’t notice the hit, think it was just a highlight. As soon as I found the job didn’t run, I noticed that the matter isn’t that simple.
We should use backslash
\ to escape the special
%. Otherwise, all data after the first
% are sent to the command as standard input.
0 1 * * * root bash /home/myname/collect/run.sh | tee /home/myname/collect/log/$(date +\%s).log
Sometimes a common, simple thing can cause a big problem for you. What you have to do is RTFM, no matter simple the thing is. Actually, we know nothing.