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System Administration Guide: Advanced Administration
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Document Information


1.  Managing Terminals and Modems (Overview)

2.  Setting Up Terminals and Modems (Tasks)

3.  Managing Serial Ports With the Service Access Facility (Tasks)

4.  Managing System Resources (Overview)

5.  Displaying and Changing System Information (Tasks)

6.  Managing Disk Use (Tasks)

7.  Managing UFS Quotas (Tasks)

8.  Scheduling System Tasks (Tasks)

Creating and Editing crontab Files (Task Map)

Ways to Automatically Execute System Tasks

For Scheduling Repetitive Jobs: crontab

For Scheduling a Single Job: at

Scheduling a Repetitive System Task (cron)

Inside a crontab File

How the cron Daemon Handles Scheduling

Syntax of crontab File Entries

Creating and Editing crontab Files

How to Create or Edit a crontab File

How to Verify That a crontab File Exists

Displaying crontab Files

How to Display a crontab File

Removing crontab Files

How to Remove a crontab File

Controlling Access to the crontab Command

How to Deny crontab Command Access

How to Limit crontab Command Access to Specified Users

How to Verify Limited crontab Command Access

Using the at Command (Task Map)

Scheduling a Single System Task (at)

Description of the at Command

Controlling Access to the at Command

How to Create an at Job

How to Display the at Queue

How to Verify an at Job

How to Display at Jobs

How to Remove at Jobs

How to Deny Access to the at Command

How to Verify That at Command Access Is Denied

9.  Managing System Accounting (Tasks)

10.  System Accounting (Reference)

11.  Managing System Performance (Overview)

12.  Managing System Processes (Tasks)

13.  Monitoring System Performance (Tasks)

14.  Troubleshooting Software Problems (Overview)

15.  Managing System Messages

16.  Managing Core Files (Tasks)

17.  Managing System Crash Information (Tasks)

18.  Troubleshooting Miscellaneous Software Problems (Tasks)

19.  Troubleshooting File Access Problems (Tasks)

20.  Resolving UFS File System Inconsistencies (Tasks)

21.  Troubleshooting Software Package Problems (Tasks)


Removing crontab Files

By default, crontab file protections are set up so that you cannot inadvertently delete a crontab file by using the rm command. Instead, use the crontab -r command to remove crontab files.

By default, the crontab -r command removes your own crontab file.

You do not have to change the directory to /var/spool/cron/crontabs (where crontab files are located) to use this command.

How to Remove a crontab File

Before You Begin

Become superuser or assume an equivalent role to remove a crontab file that belongs to root or another user. Roles contain authorizations and privileged commands.

You do not need to become superuser or assume an equivalent role to remove your own crontab file.

  1. Remove the crontab file.
    $ crontab -r [username]

    where username specifies the name of the user's account for which you want to remove a crontab file. Removing crontab files for another user requires superuser privileges.


    Caution - If you accidentally type the crontab command with no option, press the interrupt character for your editor. This character allows you to quit without saving changes. If you instead saved changes and exited the file, the existing crontab file would be overwritten with an empty file.

  2. Verify that the crontab file has been removed.
    # ls /var/spool/cron/crontabs

Example 8-5 Removing a crontab File

The following example shows how user smith uses the crontab -r command to remove his crontab file.

$ ls /var/spool/cron/crontabs
adm     jones     lp     root    smith    sys     uucp
$ crontab -r
$ ls /var/spool/cron/crontabs
adm     jones     lp     root    sys    uucp