System Administration Guide: Advanced Administration

Inside a 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 SunOS software installation. The file's contents include these 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 following describes the output for each of these command lines:

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 SunOS software installation. See the following table.

Table 8–2 Default crontab Files

crontab File







General system functions and file system cleanup 


Performance data collection 


General uucp cleanup

Besides the default crontab files, users can create crontab files to schedule their own system tasks. Other 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.

Procedures explaining how to create, edit, display, and remove crontab files are described in subsequent sections.