Basic commands to open/Edit crontab file
Editing crontab file
crontab -e
Displaying crontab file
crontab -l
Remove crontab
crontab -r
crontab syntax
cron command basically takes 6 input parameters of which each input can take multiple arguments
for that one can make use of comma or pipe separator
# min hour dom mon dow command
* * * * * (command)
Here * means for every. Above command will get executed for every minute
Detailed syntax
* * * * * command to be executed
- - - - -
| | | | |
| | | | +----- day of week (0 - 6) (Sunday=0)
| | | +------- month (1 - 12)
| | +--------- day of month (1 - 31)
| +---------- hour (0 - 23)
+------- min (0 - 59)
Example commands
# Generate progressive report for every active user at 11:45 p.m.
45 23 * * * (cd /home/sandip/current/; rake ace:daily_progressive_report RAILS_ENV=production)
# Take database backup every night
59 2 * * * (cd /home/sandip/current/; rake db:backup RAILS_ENV=production)
# Initialize grouping on database every sunday
29 3 * * 0 (cd /home/sandip/current/; rake ace:initializeCarGrouping RAILS_ENV=production)
# Generate daily stats on 4:30 AM & 12:30 PM and 4:30 PM
30 4,12,16 * * * (cd /home/sandip/current/; rake ace:daily_call_statistics RAILS_ENV=production)
# Rotate sphinx indexes updated evry hour if missed out somehow
0 * * * * (cd /user/local/bin/; indexer --rotate --config /home/sandip/current/config/production.sphinx.conf)
