tutor:Service
From Dgiref
services control
Linux has the perfect mechanism to control services: chkconfig command.
man chkconfig NAME chkconfig - updates and queries runlevel information for system ser- vices SYNOPSIS chkconfig --list [name] chkconfig --add name chkconfig --del name chkconfig [--level levels] name <on|off|reset> chkconfig [--level levels] name DESCRIPTION chkconfig provides a simple command-line tool for maintaining the /etc/rc[0-6].d directory hierarchy by relieving system administrators of the task of directly manipulating the numerous symbolic links in those directories. This implementation of chkconfig was inspired by the chkconfig command present in the IRIX operating system. Rather than maintaining configu- ration information outside of the /etc/rc[0-6].d hierarchy, however, this version directly manages the symlinks in /etc/rc[0-6].d. This leaves all of the configuration information regarding what services init starts in a single location. chkconfig has five distinct functions: adding new services for manage- ment, removing services from management, listing the current startup information for services, changing the startup information for ser- vices, and checking the startup state of a particular service. When chkconfig is run without any options, it displays usage informa- tion. If only a service name is given, it checks to see if the ser- vice is configured to be started in the current runlevel. If it is, chkconfig returns true; otherwise it returns false. The --level option may be used to have chkconfig query an alternative runlevel rather than the current one. If one of on, off, or reset is specified after the service name, chk- config changes the startup information for the specified service. The on and off flags cause the service to be started or stopped, respec- tively, in the runlevels being changed. The reset flag resets the startup information for the service to whatever is specified in the init script in question. By default, the on and off options affect only runlevels 2, 3, 4, and 5, while reset affects all of the runlevels. The --level option may be used to specify which runlevels are affected. Note that for every service, each runlevel has either a start script or a stop script. When switching runlevels, init will not re-start an already-started service, and will not re-stop a service that is not running. OPTIONS --level levels Specifies the run levels an operation should pertain to. It is given as a string of numbers from 0 to 7. For example, --level 35 specifies runlevels 3 and 5. --add name This option adds a new service for management by chkconfig. When a new service is added, chkconfig ensures that the service has either a start or a kill entry in every runlevel. If any runlevel is missing such an entry, chkconfig creates the appro- priate entry as specified by the default values in the init script. Note that default entries in LSB-delimited âINIT INFOâ sections take precedence over the default runlevels in the initscript. --del name The service is removed from chkconfig management, and any sym- bolic links in /etc/rc[0-6].d which pertain to it are removed. Note that future package installs for this service may run chk- config --add, which will re-add such links. To disable a ser- vice, run chkconfig name off. --list name This option lists all of the services which chkconfig knows about, and whether they are stopped or started in each run- level. If name is specified, information in only display about service name. RUNLEVEL FILES Each service which should be manageable by chkconfig needs two or more commented lines added to its init.d script. The first line tells chk- config what runlevels the service should be started in by default, as well as the start and stop priority levels. If the service should not, by default, be started in any runlevels, a - should be used in place of the runlevels list. The second line contains a description for the service, and may be extended across multiple lines with backslash con- tinuation. For example, random.init has these three lines: # chkconfig: 2345 20 80 # description: Saves and restores system entropy pool for \ # higher quality random number generation. This says that the random script should be started in levels 2, 3, 4, and 5, that its start priority should be 20, and that its stop prior- ity should be 80. You should be able to figure out what the descrip- tion says; the \ causes the line to be continued. The extra space in front of the line is ignored. SEE ALSO init(8) ntsysv(8) system-config-services(8) AUTHOR Erik Troan <ewt@redhat.com>
services configuration
To maintain the set of services without GUI, the ntsysv tool can be used.
man ntsysv NAME ntsysv - simple interface for configuring runlevels SYNOPSIS ntsysv [--back] [--level <levels>] DESCRIPTION ntsysv is a simple interface for configuring runlevel services which are also configurable through chkconfig. By default, it configures the cur- rent runlevel. If the user would like to configure other runlevels, those levels can be specified on the command line by listing the levels after --levels, without any spaces. For example, the option --levels 016 edits runlevels 0, 1, and 6. A service is considered to be started in the runlevel set if it is started in any of the runlevels which are being edited. The ntsysv window normally contains a Cancel button. If --back is specified, a Back button appears instead. RETURN CODES ntsysv returns 0 on success, 2 on error, and 1 if the user cancelled (or backed out of) the program. SEE ALSO chkconfig(8), serviceconf(8) AUTHOR Erik Troan <ewt@redhat.com>
