The highlights that I want to remember are:
This is used to see what is scheduled to be executed and when.
Opens the vi text editor to allow changes to the crontab. In most implementations that I have seen the changes are automatically picked up by crontab
- ESCAPE then ZZ to save changes
- ESCAPE then :q to quit and not save changes
- ESCAPE then i to go into edit mode
min hr dom month dow cmd
- minute This controls what minute of the hour the command will run on, and is between '0' and '59'
- hour This controls what hour the command will run on, and is specified in the 24 hour clock, values must be between 0 and 23 (0 is midnight)
- dom This is the Day of Month, that you want the command run on, e.g. to run a command on the 19th of each month, the dom would be 19.
- month This is the month a specified command will run on, it may be specified numerically (0-12), or as the name of the month (e.g. May)
- dow This is the Day of Week that you want a command to be run on, it can also be numeric (0-7) or as the name of the day (e.g. sun).
- user This is the user who runs the command.
- cmd This is the command that you want run. This field may contain multiple words or spaces
30 7 * * * /opt/tomcat/myApp/run.sh "This command is run daily at 7:30 am"
0 * * * * echo "This command is run hourly"
Special Keywords that can be used instead of the 5 part specifiers
@yearly 0 0 1 1 *
@daily 0 0 * * *
@hourly 0 * * * *
@reboot Run at startup.