Usage summary of chkconfig command under Linux

The chkconfig command under Linux is mainly used to query the system services executed by the system in each execution level. How to use the chkconfig command? The following small series will introduce you to the specific usage of the chkconfig command in Linux.

chkconfig command is used to update operational level information (start or stop) and query system services. Keep in mind that chkconfig does not automatically disable or activate a service immediately, it simply changes the symbolic link.

Using the syntax

The code is as follows:

chkconfig [--add][--del][--list][system service] or chkconfig [--level Level code"][system service][on/off/reset]

chkconfig displays usage when no parameters are run. If you add a service name, then check if the service is started at the current run level. If yes, return true, otherwise return false. If on, off, or reset is specified after the service name, chkconfig will change the startup information of the specified service. On and off respectively indicate that the service is started and stopped, and reset refers to the startup information of the reset service, regardless of what is specified by the problematic initialization script. On and off switches, the system is only valid for run levels 3, 4, 5 by default, but reset can be active for all run levels.

Parameter Usage

The code is as follows:

--add Adds the specified system service, allows the chkconfig command to manage it, and adds it to the system-initiated narration file. related data.

--del Deletes the specified system service, no longer managed by the chkconfig command, and deletes the relevant data in the system-initiated narrative file.

--level "Level Code" Specifies in which execution level the read system service is to be turned on or off.

Level 0 means: Indicates shutdown

Level 1 means: Single User Mode

Level 2 means: Multi-user command line mode without network connection

Level 3 means: Multi-user command line mode with network connection

Level 4 means: Not available

Level 5 means: Multi-user mode with graphical interface

Level 6 Representation: Restart

It should be noted that the level option can specify the runlevel to be viewed and not necessarily the current runlevel. There can only be one startup script or stop script for each run level. When switching the run level, init will not restart the already started service, nor will it stop the stopped service again.

The code is as follows:

chkconfig --list [name]: Displays the running status information (on or off) of all runtime system services. If name is specified, only the status of the specified service at different run levels is displayed.

chkconfig --add name: Add a new service. Chkconfig ensures that each run level has a start (S) or kill (K) entry. If it is missing, it will be automatically created from the default init script.

chkconfig --del name: Delete the service and remove the associated symbolic link from /etc/rc[0-6].d.

chkconfig [--level levels] name: Set whether a service is started, stopped or reset at the specified run level.

Runlevel Files

Each service managed by chkconfig requires two or more lines of comments in the script under the corresponding init.d. The first line tells chkconfig the run level of the default start and the priority of start and stop. If a service is not started by default at any runlevel, use – instead of the runlevel. The second line describes the service and can be commented with \\ cross-row.

For example, random.init contains three lines:

The code is as follows:

# chkconfig: 2345 20 80

# description: Saves and restores system entropy Pool for \\

# higher quality random number generation.

Using the examples

The code is as follows:

chkconfig --list #List all system services

chkconfig --add httpd #add httpd service

chkconfig --del httpd #delete httpd service

chkconfig --level httpd 2345 on #Set httpd at runlevel 2, 3, 4, 5 are all on (on) state

chkconfig --list # List all system service startup conditions

chkconfig --list mysqld #column The mysqld service settings

chkconfig --level 35 mysqld on #Set mysqld to run the service at levels 3 and 5, --level 35 means the operation is only performed at levels 3 and 5, on means start, Off means to close

chkconfig mysqld on #Set mysqld to be on each level, “ Rdquo; includes 2, 3, 4, 5 levels

How to add a service

Service scripts must be stored in the /etc/ini.d/directory;

chkconfig &ndash ;add servicename, add this service to the chkconfig tool service list, the service will be given K/S entry in /etc/rc.d/rcN.d;

chkconfig –level 35 mysqld On, modify the default startup level of the service.

The above is the introduction of the chkconfig command under Linux. I believe that you have a good understanding of the chkconfig command through this article. If you want to know more about Linux commands, you may wish to pay more attention to this website. .