Cron cheatsheet
Syntax
| * | * | * | * | * | /path/to/command.sh |
| 1 | 2 | 3 | 4 | 5 | 6 |
| Key | Contents | Range |
| 1 | Minute of hour | 0-59 |
| 2 | Hour of day | 0-23 |
| 3 | Day of month | 1-31 |
| 4 | Month of year | 1-12 |
| 5 | Day of week | 0-6 (0=Sunday) |
| 6 | Command to run (full path) | |
Crontab examples
#comments start with #.
#you cannot mix comments and commands on the same line.
#force command output to be mailed to specific user
MAILTO="admin@myserver.com"
#or send all command output to the bitbucket
MAILTO=""
/5 * * * * /usr/bin/mrtg /data/mrtg/172.25.0.1.cfg --logging /var/log/mrtg.log
2 11,15 * * * /data/scripts/portprobe-0.5.pl
*/5 means run every 5 minutes
2 11,15 means run 11:02 and 15:02 every day
Meaning of *
| Field | |
| 1 | Do job every minute, 60 times per hour |
| 2 | Do job every hour, 24 times per day |
| 3 | Ignore this field and use field 5 |
| 4 | Do job every month, 12 times per year |
| 5 | Ignore this field and use field 3 |
| | Asterisk in both field 3 & 5 means job is run every day |
Summary
# * * * * * 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)
