What is rc.status file in linux

Question

I am creating a linux service, in the skeleton file it is mentioned that we need to run various rc commands (rc-status, rc_reset) to update the status of the service. What does it mean? I was looking for him, but could not find many details. Can someone help me

Answer 1

The commands from rc.status are actually SuSe specific. AFAICT they handle two things: the output to the user and the final status of the return script. rc_status checks to see if the previous command succeeded (i.e., start / restart / stop the service) and sets the “status value”, which is the return value returned by rc_exit (which you put at the end of the .d script initialization). A source

You can probably write your shell script without them, but I believe that they help make sure your script meets LSB requirements and works well with other system scripts. I bet most of them are actually documented in the /etc/rc.status file. I just don't have a convenient box.

Answer 2

You need a shell script to stop / start / restart the service and indicate its status. They are usually called rc scripts. Look in the /etc/init.d directory to see some examples - / etc / init.d / klogd is pretty simple.

The reason they are in init.d is because they must also start automatically at boot in order to restore the service.

Each version of Linux tends to be slightly different from how the boot works, but the Debian system is pretty typical as it is the basis for many other distributions - see Debian Download Manager

Answer 3

Here is the comment block from /etc/init.d/skeleton from SUSE Linux Enterprise Server 11 SP3:

 #!/bin/sh # # Template SUSE system startup script for example service/daemon FOO # Copyright (C) 1995--2005 Kurt Garloff, SUSE / Novell Inc. # # This library is free software; you can redistribute it and/or modify it # under the terms of the GNU Lesser General Public License as published by # the Free Software Foundation; either version 2.1 of the License, or (at # your option) any later version. # # This library is distributed in the hope that it will be useful, but # WITHOUT ANY WARRANTY; without even the implied warranty of # MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU # Lesser General Public License for more details. # # You should have received a copy of the GNU Lesser General Public # License along with this library; if not, write to the Free Software # Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307, # USA. # # /etc/init.d/FOO # and its symbolic link # /(usr/)sbin/rcFOO # # Template system startup script for some example service/daemon FOO # # LSB compatible service control script; see http://www.linuxbase.org/spec/ # # Note: This template uses functions rc_XXX defined in /etc/rc.status on # UnitedLinux/SUSE/Novell based Linux distributions. If you want to base your # script on this template and ensure that it works on non UL based LSB # compliant Linux distributions, you either have to provide the rc.status # functions from UL or change the script to work without them. # See skeleton.compat for a template that works with other distros as well. # ### BEGIN INIT INFO # Provides: FOO # Required-Start: $syslog $remote_fs # Should-Start: $time ypbind smtp # Required-Stop: $syslog $remote_fs # Should-Stop: ypbind smtp # Default-Start: 3 5 # Default-Stop: 0 1 2 6 # Short-Description: FOO XYZ daemon providing ZYX # Description: Start FOO to allow XY and provide YZ # continued on second line by '#<TAB>' # should contain enough info for the runlevel editor # to give admin some idea what this service does and # what it needed for ... # (The Short-Description should already be a good hint.) ### END INIT INFO # # Any extensions to the keywords given above should be preceeded by # X-VendorTag- (X-UnitedLinux- X-SuSE- for us) according to LSB. # # Notes on Required-Start/Should-Start: # * There are two different issues that are solved by Required-Start # and Should-Start # (a) Hard dependencies: This is used by the runlevel editor to determine # which services absolutely need to be started to make the start of # this service make sense. Example: nfsserver should have # Required-Start: $portmap # Also, required services are started before the dependent ones. # The runlevel editor will warn about such missing hard dependencies # and suggest enabling. During system startup, you may expect an error, # if the dependency is not fulfilled. # (b) Specifying the init script ordering, not real (hard) dependencies. # This is needed by insserv to determine which service should be # started first (and at a later stage what services can be started # in parallel). The tag Should-Start: is used for this. # It tells, that if a service is available, it should be started # before. If not, never mind. # * When specifying hard dependencies or ordering requirements, you can # use names of services (contents of their Provides: section) # or pseudo names starting with a $. The following ones are available # according to LSB (1.1): # $local_fs all local file systems are mounted # (most services should need this!) # $remote_fs all remote file systems are mounted # (note that /usr may be remote, so # many services should Require this!) # $syslog system logging facility up # $network low level networking (eth card, ...) # $named hostname resolution available # $netdaemons all network daemons are running # The $netdaemons pseudo service has been removed in LSB 1.2. # For now, we still offer it for backward compatibility. # These are new (LSB 1.2): # $time the system time has been set correctly # $portmap SunRPC portmapping service available # UnitedLinux extensions: # $ALL indicates that a script should be inserted # at the end # * The services specified in the stop tags # (Required-Stop/Should-Stop) # specify which services need to be still running when this service # is shut down. Often the entries there are just copies or a subset # from the respective start tag. # * Should-Start/Stop are now part of LSB as of 2.0, # formerly SUSE/Unitedlinux used X-UnitedLinux-Should-Start/-Stop. # insserv does support both variants. # * X-UnitedLinux-Default-Enabled: yes/no is used at installation time # (%fillup_and_insserv macro in %post of many RPMs) to specify whether # a startup script should default to be enabled after installation. # It not used by insserv. # # Note on runlevels: # 0 - halt/poweroff 6 - reboot # 1 - single user 2 - multiuser without network exported # 3 - multiuser w/ network (text mode) 5 - multiuser w/ network and X11 (xdm) # # Note on script names: # http://www.linuxbase.org/spec/refspecs/LSB_1.3.0/gLSB/gLSB/scrptnames.html # A registry has been set up to manage the init script namespace. # http://www.lanana.org/ # Please use the names already registered or register one or use a # vendor prefix. #... # Source LSB init functions # providing start_daemon, killproc, pidofproc, # log_success_msg, log_failure_msg and log_warning_msg. # This is currently not used by UnitedLinux based distributions and # not needed for init scripts for UnitedLinux only. If it is used, # the functions from rc.status should not be sourced or used. #. /lib/lsb/init-functions # # Shell functions sourced from /etc/rc.status: # rc_check check and set local and overall rc status # rc_status check and set local and overall rc status # rc_status -v be verbose in local rc status and clear it afterwards # rc_status -v -r ditto and clear both the local and overall rc status # rc_status -s display "skipped" and exit with status 3 # rc_status -u display "unused" and exit with status 3 # rc_failed set local and overall rc status to failed # rc_failed <num> set local and overall rc status to <num> # rc_reset clear both the local and overall rc status # rc_exit exit appropriate to overall rc status # rc_active checks whether a service is activated by symlinks #... # # Return values acc. to LSB for all commands but status: # 0 - success # 1 - generic or unspecified error # 2 - invalid or excess argument(s) # 3 - unimplemented feature (eg "reload") # 4 - user had insufficient privileges # 5 - program is not installed # 6 - program is not configured # 7 - program is not running # 8--199 - reserved (8--99 LSB, 100--149 distrib, 150--199 appl) # # Note that starting an already running service, stopping # or restarting a not-running service as well as the restart # with force-reload (in case signaling is not supported) are # considered a success. #... ## Check status with checkproc(8), if process is running ## checkproc will return with exit status 0. # # Return value is slightly different for the status command: # 0 - service up and running # 1 - service dead, but /var/run/ pid file exists # 2 - service dead, but /var/lock/ lock file exists # 3 - service not running (unused) # 4 - service status unknown :-( # 5--199 reserved (5--99 LSB, 100--149 distro, 150--199 appl.) 

Here is the comment block from /etc/rc.status from SUSE Linux Enterprise Server 11 SP3:

 # /etc/rc.status # vim: syntax=sh # Definition of boot script return messages # # The bootscripts should use the variables rc_done and rc_failed to # report whether they failed or succeeded. See /etc/init.d/skeleton for # an example how the shell functions rc_status and rc_reset are used. # # These functions make use of the variables rc_done and rc_failed; # rc_done_up and rc_failed_up are the same as rc_done and rc_failed # but contain a terminal code to move up one line before the output # of the actual string. (This is particularly useful when the script # starts a daemon which produces user output with a newline character) # # The variable rc_reset is used by the master resource control script # /etc/init.d/rc to turn off all attributes and switch to the standard # character set. # # \033 ascii ESCape # \033[<NUM>G move to column <NUM> (linux console, xterm, not vt100) # \033[<NUM>C move <NUM> columns forward but only upto last column # \033[<NUM>D move <NUM> columns backward but only upto first column # \033[<NUM>A move <NUM> rows up # \033[<NUM>B move <NUM> rows down # \033[1m switch on bold # \033[31m switch on red # \033[32m switch on green # \033[33m switch on yellow # \033[m switch off color/bold # \017 exit alternate mode (xterm, vt100, linux console) # \033[10m exit alternate mode (linux console) # \015 carriage return (without newline)