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Managing System Information, Processes, and Performance in Oracle® Solaris 11.4

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Updated: April 2019
 
 

About the crontab File

The cron daemon schedules system tasks according to commands found within each crontab file. A crontab file consists of commands, one command per line, that will be executed at regular intervals. The beginning of each line contains date and time information that tells the cron daemon when to execute the command.

For example, a crontab file named root is supplied during the Oracle Solaris software installation. The file's contents include the following command lines:

10 3 * * * /usr/sbin/logadm (1)
15 3 * * 0 /usr/lib/fs/nfs/nfsfind (2)
1 2 * * * [ -x /usr/sbin/rtc ] && /usr/sbin/rtc -c > /dev/null 2>&1 (3)
30 3 * * * [ -x /usr/lib/gss/gsscred_clean ] && /usr/lib/gss/gsscred_clean (4)

    The output for each of these command lines is as follows:

  • The first line runs the logadm command at 3:10 am every day.

  • The second line executes the nfsfind script every Sunday at 3:15 am.

  • The third line runs a script that checks for daylight savings time (and make corrections, if necessary) at 2:10 am daily.

    If there is no RTC time zone or /etc/rtc_config file, this entry does nothing.


    x86 only -  The /usr/sbin/rtc script can be run only on an x86 based system.
  • The fourth line checks for (and removes) duplicate entries in the Generic Security Service table, /etc/gss/gsscred_db, at 3:30 am daily.

For more information about the syntax of lines within a crontab file, see Syntax of crontab File Entries.

The crontab files are stored in the /var/spool/cron/crontabs directory. Several crontab files besides root are provided during Oracle Solaris software installation.

adm

Accounting

root

General system functions and file system cleanup

sys

Performance data collection

uucp

General uucp cleanup

Besides the default crontab files, you can create crontab files to schedule your own system tasks. Custom crontab files are named after the user accounts in which they are created, such as bob, mary, smith, or jones.

To access crontab files that belong to root or other users, superuser privileges are required.