What is rc.status file in linux - 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 service status. What does this actually mean. I have googled it but not able find many details. Can somebody help me

Answer 1

The commands from rc.status are actually SuSe specific I think. AFAICT they handle two things: output to the user and the final return status of the script. rc_status checks if the previous command (i.e. the start/restart/stop of a service) executed successfully and sets the "status value", which is the return value returned by rc_exit (which you place at the end of your init.d script). Source
You can conceivably write your shell script without them, but I assume they help making sure that your script conforms to LSB requirements and blends in well with other system scripts. I bet most of this is actually documented in the /etc/rc.status file, though. I just don't have a suse box handy.

Answer 2

You need a shell script to stop/start/restart your service and to give its status.
These are generally called rc scripts. Have a look in directory /etc/init.d to see some examples - /etc/init.d/klogd is quite a simple one.
The reason they are in init.d is because they also need to be run automatically at boot up to restore the service.
Each Linux variant tends to be a bit different on how the boot up works but the Debian system is fairly typical as it is the basis for many other distributions - see Debian Boot Up Manager

Answer 3

Here is the comments 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's 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's 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 (e.g. "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 comments 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)