Steps for customizing the cron daemon

Before you begin: You need to make sure that several files have the correct settings.

The at, batch, and crontab executable program files must be owned by a UID(0) user, and the setuid bit must be set. To check the settings, issue:
```
ls -E /bin/at /bin/batch /bin/crontab
```
The cron executable program file must have the setuid bit off and the program control attribute set. To check the settings, issue:
```
ls -E /usr/sbin/cron
```

Perform the following steps to set up the cron daemon.

Copy /samples/queuedefs to /usr/lib/cron/queuedefs.
Example:
```
cp /samples/queuedefs /usr/lib/cron/queuedefs
```
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Set up the queue definitions in the /usr/lib/cron/queuedefs file.
Example:
```
c.5j2n15w
```
c

Queue name. The default queue name for crontab jobs isc.

5

Number of jobs running at the same time. Set this to the appropriate value for your installation.

2

The nice value mapped to the PRIORITYGOAL or PRIORITYPG statement in BPXPRMxx. Set this to the appropriate value for your installation.

15

If five jobs are already running, wait 15 seconds before trying the next job.
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Create lists for allowed and denied users for the crontab command:
- Allowed users: /usr/lib/cron/cron.allow
- Denied users: /usr/lib/cron/cron.deny
Tip: To give access to all users, create an empty cron.deny file and do not create an cron.allow file.

_______________________________________________________________
Create lists for allowed and denied users for the at command:
- Allowed users: /usr/lib/cron/at.allow
- Denied users: /usr/lib/cron/at.deny
Tip: To give access to all users, create an empty at.deny file and do not create an at.allow file.

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Set the TZ environment variable as described in z/OS UNIX System Services Command Reference. cron uses this time zone when matching the crontab entries. at jobs use the TZ of the user.
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When you are done, the cron daemon has been customized and can be started.

It must be started by a user ID with READ permission to the BPX.DAEMON resource profile in the FACILITY class. (For more information about BPX.DAEMON, see Setting up the UNIX-related FACILITY and SURROGAT class profiles and Establishing the correct level of security for daemons.)
It is typically called from /etc/rc. The command is:
```
_BPX_JOBNAME=CROND /usr/sbin/cron &
```
As explained in Using & at the end of a command, using the & at the end of a command starts the command in the background and the _BPX_JOBNAME environment variable assigns a job name to the cron daemon.
The cron daemon can only be started once because it will continue to run in the background.

For more information about starting daemons, see Starting daemons.

Note:

Because cron might try to send mail, you might want to configure the mailx utility as described in Customizing electronic mail.
The job log file is in /usr/spool/cron/log and can be used when debugging. The log file must be periodically archived and cleaned up or it will grow too large.