/lib/lsb/init-functions文件解析
零、背景
在玩AppArmor的时候涉及到了/etc/init.d/apparmor（无论是sudo /etc/init.d/apparmor start还是sudo systemctl start apparmor.service），而这个文件又涉及到了另一个文件、也就是本文的主角：/lib/lsb/init-functions。
执行sudo /etc/init.d/apparmor start命令时结果如下：
$ sudo /etc/init.d/apparmor start
/etc/init.d/apparmor:行43: /lib/lsb/init-functions: 没有那个文件或目录
而执行sudo systemctl start apparmor.services时结果如下：
$ sudo systemctl start apparmor
Job for apparmor.service failed because the control process exited with error code.
See "systemctl status apparmor.service" and "journalctl -xeu apparmor.service" for details.
通过systemctl status apparmor.service查看状态，结果如下：
$ systemctl status apparmor.service
× apparmor.service - LSB: AppArmor initializationLoaded: loaded (/etc/init.d/apparmor; generated)Active: failed (Result: exit-code) since Thu 2023-04-20 16:29:35 CST; 1min 29s agoDocs: man:systemd-sysv-generator(8)Process: 2489718 ExecStart=/etc/init.d/apparmor start (code=exited, status=1/FAILURE)CPU: 8ms$ sudo systemctl status apparmor.service
× apparmor.service - LSB: AppArmor initializationLoaded: loaded (/etc/init.d/apparmor; generated)Active: failed (Result: exit-code) since Thu 2023-04-20 16:29:35 CST; 1min 39s agoDocs: man:systemd-sysv-generator(8)Process: 2489718 ExecStart=/etc/init.d/apparmor start (code=exited, status=1/FAILURE)CPU: 8ms4月 20 16:29:35 Ding-Perlis-MP260S48 systemd[1]: Starting LSB: AppArmor initialization...
4月 20 16:29:35 Ding-Perlis-MP260S48 apparmor[2489718]: /etc/init.d/apparmor:行43: /lib/lsb/init-functions: 没有那个文件或目录4月 20 16:29:35 Ding-Perlis-MP260S48 systemd[1]: apparmor.service: Control process exited, code=exited, status=1/FAILURE
4月 20 16:29:35 Ding-Perlis-MP260S48 systemd[1]: apparmor.service: Failed with result 'exit-code'.
4月 20 16:29:35 Ding-Perlis-MP260S48 systemd[1]: Failed to start LSB: AppArmor initialization.
可以看到，失败的根本原因就是没有/lib/lsb/init-functions文件。
先来看一下/etc/init.d/apparmor文件中是怎样与/lib/lsb/init-functions文件联系的。/etc/init.d/apparmor文件片段如下：
APPARMOR_FUNCTIONS=/lib/apparmor/rc.apparmor.functions# Functions needed by rc.apparmor.functions. /lib/lsb/init-functions
……# Source AppArmor function library
if [ -f "${APPARMOR_FUNCTIONS}" ]; then. ${APPARMOR_FUNCTIONS}
elseaa_log_failure_msg "Unable to find AppArmor initscript functions"exit 1
fi
通过以上代码片段就可以看出，如果/lib/lsb/init-functions文件，则/etc/init.d/apparmor的第43行代码. /lib/lsb/init-functions就会导致以上错误。
那么这个/lib/lsb/init-fiunctions到底是何方神圣？其作用和内容又是怎样的？接下来就进行完全解析。
一、简介
根据ChatGPT的搜索结果（poe.com/ChatGPT），/lib/lsb/init-functions文件的介绍如下：
/lib/lsb/init-functions文件是一个Linux系统上的脚本文件，它包含了一些常用的函数，用于在系统启动时执行各种任务。这个文件通常被用来编写启动脚本，比如在系统启动时自动启动某个服务。
这个文件提供了许多函数，比如：
log_success_msg：用于记录启动成功的消息；
log_failure_msg：用于记录启动失败的消息；
log_warning_msg：用于记录启动警告的消息；
log_progress_msg：用于记录启动进度的消息；
pidofproc：用于获取某个进程的PID；
killproc：用于杀死某个进程；
start_daemon：用于启动一个后台进程。
这些函数可以让脚本编写者更加方便地编写启动脚本，同时也提高了启动脚本的可读性和可维护性。
再来看看/lib/lsb文件夹是干什么的：
/lib/lsb是一个目录，它通常包含了一些用于支持Linux Standard Base（LSB）规范的文件和脚本。LSB是一种标准，旨在使不同的Linux发行版之间更加兼容，从而提高应用程序在各种Linux发行版上的可移植性。
在/lib/lsb目录中，常见的文件和目录包括：
- init-functions：包含了一些常用的函数，用于在系统启动时执行各种任务，如启动服务等；
- lsb_release：用于显示当前系统的LSB版本和发行版信息；
- lsb_log_message：用于在系统日志中记录LSB兼容的日志信息；
- /etc/lsb-release：包含了当前系统的LSB版本和发行版信息，可以被其他脚本和程序引用。
这些文件和脚本可以帮助系统管理员编写LSB兼容的启动脚本和管理工具，从而提高系统的可移植性和可维护性。
笔者的Ubuntu系统（Ubuntu 22.04.1 LTS）电脑中的/lib/lsb/目录下倒是没有那么多文件和文件夹，如下：
$ ls /lib/lsb/
init-functions init-functions.d$ tree /lib/lsb
/lib/lsb
├── init-functions
└── init-functions.d├── 00-verbose├── 40-systemd├── 50-ubuntu-logging└── 99-plymouth1 directory, 5 files
二、代码分析
通过上边介绍，已经对/lib/lsb/init-functions文件有了大致的了解。趁热打铁，结合概述看一下其源码：
# /lib/lsb/init-functions for Debian -*- shell-script -*-
#
#Copyright (c) 2002-08 Chris Lawrence
#All rights reserved.
#
#Redistribution and use in source and binary forms, with or without
#modification, are permitted provided that the following conditions
#are met:
#1. Redistributions of source code must retain the above copyright
# notice, this list of conditions and the following disclaimer.
#2. Redistributions in binary form must reproduce the above copyright
# notice, this list of conditions and the following disclaimer in the
# documentation and/or other materials provided with the distribution.
#3. Neither the name of the author nor the names of other contributors
# may be used to endorse or promote products derived from this software
# without specific prior written permission.
#
#THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
#IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
#WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
#ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE
#LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
#CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
#SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR
#BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
#WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE
#OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE,
#EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.start_daemon () {local force nice pidfile exec args OPTINDforce=""nice=0pidfile=/dev/nullOPTIND=1while getopts fn:p: opt ; docase "$opt" inf) force="force";;n) nice="$OPTARG";;p) pidfile="$OPTARG";;esacdoneshift $(($OPTIND - 1))if [ "$1" = '--' ]; thenshiftfiexec="$1"; shiftargs="--start --nicelevel $nice --quiet --oknodo"if [ "$force" ]; then/sbin/start-stop-daemon $args \\--chdir "$PWD" --startas $exec --pidfile /dev/null -- "$@"elif [ $pidfile ]; then/sbin/start-stop-daemon $args \\--chdir "$PWD" --exec $exec --oknodo --pidfile "$pidfile" -- "$@"else/sbin/start-stop-daemon $args --chdir "$PWD" --exec $exec -- "$@"fi
}pidofproc () {local pidfile base status specified pid OPTINDpidfile=specified=OPTIND=1while getopts p: opt ; docase "$opt" inp) pidfile="$OPTARG"specified="specified";;esacdoneshift $(($OPTIND - 1))if [ $# -ne 1 ]; thenecho "$0: invalid arguments" >&2return 4fibase=${1##*/}if [ ! "$specified" ]; thenpidfile="/var/run/$base.pid"fiif [ -n "${pidfile:-}" ]; thenif [ -e "$pidfile" ]; thenif [ -r "$pidfile" ]; thenread pid < "$pidfile"if [ -n "${pid:-}" ]; thenif $(kill -0 "${pid:-}" 2> /dev/null); thenecho "$pid" || truereturn 0elif ps "${pid:-}" >/dev/null 2>&1; thenecho "$pid" || truereturn 0 # program is running, but not owned by this userelsereturn 1 # program is dead and /var/run pid file existsfifielsereturn 4 # pid file not readable, hence status is unknown.fielse# pid file doesn't exist, try to find the pid neverthelessif [ -x /bin/pidof ] && [ ! "$specified" ]; thenstatus="0"/bin/pidof -c -o %PPID -x $1 || status="$?"if [ "$status" = 1 ]; thenreturn 3 # program is not runningfireturn 0fireturn 3 # specified pid file doesn't exist, program probably stoppedfifiif [ "$specified" ]; thenreturn 3 # almost certain it's not runningfireturn 4 # Unable to determine status
}# start-stop-daemon uses the same algorithm as "pidofproc" above.
killproc () {local pidfile sig status base name_param is_term_sig OPTINDpidfile=name_param=is_term_sig=OPTIND=1while getopts p: opt ; docase "$opt" inp) pidfile="$OPTARG";;esacdoneshift $(($OPTIND - 1))base=${1##*/}if [ ! $pidfile ]; thenname_param="--name $base --pidfile /var/run/$base.pid"elsename_param="--name $base --pidfile $pidfile"fisig=$(echo ${2:-} | sed -e 's/^-\\(.*\\)/\\1/')sig=$(echo $sig | sed -e 's/^SIG\\(.*\\)/\\1/')if [ "$sig" = 15 ] || [ "$sig" = TERM ]; thenis_term_sig="terminate_signal"fistatus=0if [ ! "$is_term_sig" ]; thenif [ -n "$sig" ]; then/sbin/start-stop-daemon --stop --signal "$sig" \\--quiet $name_param || status="$?"else/sbin/start-stop-daemon --stop \\--retry 5 \\--quiet $name_param || status="$?"fielse/sbin/start-stop-daemon --stop --quiet \\--oknodo $name_param || status="$?"fiif [ "$status" = 1 ]; thenif [ -z "$sig" ]; thenreturn 0fireturn 3 # program is not runningfiif [ "$status" = 0 ] && [ "$is_term_sig" ] && [ "$pidfile" ]; thenpidofproc -p "$pidfile" "$1" >/dev/null || rm -f "$pidfile"fireturn 0
}# Return LSB status
status_of_proc () {local pidfile daemon name status OPTINDpidfile=OPTIND=1while getopts p: opt ; docase "$opt" inp) pidfile="$OPTARG";;esacdoneshift $(($OPTIND - 1))if [ -n "$pidfile" ]; thenpidfile="-p $pidfile"fidaemon="$1"name="$2"status="0"pidofproc $pidfile $daemon >/dev/null || status="$?"if [ "$status" = 0 ]; thenlog_success_msg "$name is running"return 0elif [ "$status" = 4 ]; thenlog_failure_msg "could not access PID file for $name"return $statuselselog_failure_msg "$name is not running"return $statusfi
}log_use_fancy_output () {TPUT=/usr/bin/tputEXPR=/usr/bin/exprif [ -t 1 ] &&[ "x${TERM:-}" != "x" ] &&[ "x${TERM:-}" != "xdumb" ] &&[ -x $TPUT ] && [ -x $EXPR ] &&$TPUT hpa 60 >/dev/null 2>&1 &&$TPUT setaf 1 >/dev/null 2>&1then[ -z $FANCYTTY ] && FANCYTTY=1 || trueelseFANCYTTY=0ficase "$FANCYTTY" in1|Y|yes|true) true;;*) false;;esac
}log_success_msg () {if [ -n "${1:-}" ]; thenlog_begin_msg $@filog_end_msg 0
}log_failure_msg () {if [ -n "${1:-}" ]; thenlog_begin_msg $@ "..."filog_end_msg 1 || true
}log_warning_msg () {if [ -n "${1:-}" ]; thenlog_begin_msg $@ "..."filog_end_msg 255 || true
}#
# NON-LSB HELPER FUNCTIONS
#
# int get_lsb_header_val (char *scriptpathname, char *key)
get_lsb_header_val () {if [ ! -f "$1" ] || [ -z "${2:-}" ]; thenreturn 1fiLSB_S="### BEGIN INIT INFO"LSB_E="### END INIT INFO"sed -n "/$LSB_S/,/$LSB_E/ s/# $2: \\+\\(.*\\)/\\1/p" "$1"
}# If the currently running init daemon is upstart, return zero; if the
# calling init script belongs to a package which also provides a native
# upstart job, it should generally exit non-zero in this case.
init_is_upstart()
{if [ -x /sbin/initctl ] && /sbin/initctl version 2>/dev/null | /bin/grep -q upstart; thenreturn 0fireturn 1
}# int log_begin_message (char *message)
log_begin_msg () {log_begin_msg_pre "$@"if [ -z "${1:-}" ]; thenreturn 1fiecho -n "$@" || truelog_begin_msg_post "$@"
}# Sample usage:
# log_daemon_msg "Starting GNOME Login Manager" "gdm"
#
# On Debian, would output "Starting GNOME Login Manager: gdm"
# On Ubuntu, would output " * Starting GNOME Login Manager..."
#
# If the second argument is omitted, logging suitable for use with
# log_progress_msg() is used:
#
# log_daemon_msg "Starting remote filesystem services"
#
# On Debian, would output "Starting remote filesystem services:"
# On Ubuntu, would output " * Starting remote filesystem services..."log_daemon_msg () {if [ -z "${1:-}" ]; thenreturn 1filog_daemon_msg_pre "$@"if [ -z "${2:-}" ]; thenecho -n "$1:" || truereturnfiecho -n "$1: $2" || truelog_daemon_msg_post "$@"
}# #319739
#
# Per policy docs:
#
# log_daemon_msg "Starting remote file system services"
# log_progress_msg "nfsd"; start-stop-daemon --start --quiet nfsd
# log_progress_msg "mountd"; start-stop-daemon --start --quiet mountd
# log_progress_msg "ugidd"; start-stop-daemon --start --quiet ugidd
# log_end_msg 0
#
# You could also do something fancy with log_end_msg here based on the
# return values of start-stop-daemon; this is left as an exercise for
# the reader...
#
# On Ubuntu, one would expect log_progress_msg to be a no-op.
log_progress_msg () {if [ -z "${1:-}" ]; thenreturn 1fiecho -n " $@" || true
}# int log_end_message (int exitstatus)
log_end_msg () {# If no arguments were passed, returnif [ -z "${1:-}" ]; thenreturn 1filocal retvalretval=$1log_end_msg_pre "$@"# Only do the fancy stuff if we have an appropriate terminal# and if /usr is already mountedif log_use_fancy_output; thenRED=$( $TPUT setaf 1)YELLOW=$( $TPUT setaf 3)NORMAL=$( $TPUT op)elseRED=''YELLOW=''NORMAL=''fiif [ $1 -eq 0 ]; thenecho "." || trueelif [ $1 -eq 255 ]; then/bin/echo -e " ${YELLOW}(warning).${NORMAL}" || trueelse/bin/echo -e " ${RED}failed!${NORMAL}" || truefilog_end_msg_post "$@"return $retval
}log_action_msg () {log_action_msg_pre "$@"echo "$@." || truelog_action_msg_post "$@"
}log_action_begin_msg () {log_action_begin_msg_pre "$@"echo -n "$@..." || truelog_action_begin_msg_post "$@"
}log_action_cont_msg () {echo -n "$@..." || true
}log_action_end_msg () {local endlog_action_end_msg_pre "$@"if [ -z "${2:-}" ]; thenend="."elseend=" ($2)."fiif [ $1 -eq 0 ]; thenecho "done${end}" || trueelseif log_use_fancy_output; thenRED=$( $TPUT setaf 1)NORMAL=$( $TPUT op)/bin/echo -e "${RED}failed${end}${NORMAL}" || trueelseecho "failed${end}" || truefifilog_action_end_msg_post "$@"
}# Pre&Post empty function declaration, to be overriden from /lib/lsb/init-functions.d/*
log_daemon_msg_pre () { :; }
log_daemon_msg_post () { :; }
log_begin_msg_pre () { :; }
log_begin_msg_post () { :; }
log_end_msg_pre () { :; }
log_end_msg_post () { :; }
log_action_msg_pre () { :; }
log_action_msg_post () { :; }
log_action_begin_msg_pre () { :; }
log_action_begin_msg_post () { :; }
log_action_end_msg_pre () { :; }
log_action_end_msg_post () { :; }# Include hooks from other packages in /lib/lsb/init-functions.d
for hook in $(run-parts --lsbsysinit --list /lib/lsb/init-functions.d 2>/dev/null); do[ -r $hook ] && . $hook || true
doneFANCYTTY=
[ -e /etc/lsb-base-logging.sh ] && . /etc/lsb-base-logging.sh || true本文只关注与/etc/init.d/apparmor相关的函数。下边逐一进行分析：
- log_daemon_msg函数
代码如下：
# Sample usage:
# log_daemon_msg "Starting GNOME Login Manager" "gdm"
#
# On Debian, would output "Starting GNOME Login Manager: gdm"
# On Ubuntu, would output " * Starting GNOME Login Manager..."
#
# If the second argument is omitted, logging suitable for use with
# log_progress_msg() is used:
#
# log_daemon_msg "Starting remote filesystem services"
#
# On Debian, would output "Starting remote filesystem services:"
# On Ubuntu, would output " * Starting remote filesystem services..."log_daemon_msg () {if [ -z "${1:-}" ]; thenreturn 1filog_daemon_msg_pre "$@"if [ -z "${2:-}" ]; thenecho -n "$1:" || truereturnfiecho -n "$1: $2" || truelog_daemon_msg_post "$@"
}- log_end_msg函数
代码如下：
# int log_end_message (int exitstatus)
log_end_msg () {# If no arguments were passed, returnif [ -z "${1:-}" ]; thenreturn 1filocal retvalretval=$1log_end_msg_pre "$@"# Only do the fancy stuff if we have an appropriate terminal# and if /usr is already mountedif log_use_fancy_output; thenRED=$( $TPUT setaf 1)YELLOW=$( $TPUT setaf 3)NORMAL=$( $TPUT op)elseRED=''YELLOW=''NORMAL=''fiif [ $1 -eq 0 ]; thenecho "." || trueelif [ $1 -eq 255 ]; then/bin/echo -e " ${YELLOW}(warning).${NORMAL}" || trueelse/bin/echo -e " ${RED}failed!${NORMAL}" || truefilog_end_msg_post "$@"return $retval
}- log_daemon_msg_pre、log_daemon_msg_post、log_end_msg_pre、log_end_msg_post
log_daemon_msg_pre、log_daemon_msg_post、log_end_msg_pre、log_end_msg_post等函数在同文件（/lib/lsb/init-functions）中，如下：
# Pre&Post empty function declaration, to be overriden from /lib/lsb/init-functions.d/*
log_daemon_msg_pre () { :; }
log_daemon_msg_post () { :; }
log_begin_msg_pre () { :; }
log_begin_msg_post () { :; }
log_end_msg_pre () { :; }
log_end_msg_post () { :; }
log_action_msg_pre () { :; }
log_action_msg_post () { :; }
log_action_begin_msg_pre () { :; }
log_action_begin_msg_post () { :; }
log_action_end_msg_pre () { :; }
log_action_end_msg_post () { :; }根据注释，这些函数在/lib/lsb/init-functions.d/下重载，没有重载的函数就是使用以上默认的空函数。笔者电脑上/lib/lsb/init-functions.d/下的内容如下（上边实际上已经列出了）：
$ ls /lib/lsb/init-functions.d/
00-verbose 40-systemd 50-ubuntu-logging 99-plymouth
这里只列出50-ubuntu-logging文件的内容，如下：
# Default init script logging functions suitable for Ubuntu.
# See /lib/lsb/init-functions for usage help.
LOG_DAEMON_MSG=""log_use_plymouth () {if [ "${loop:-n}" = y ]; thenreturn 1fiplymouth --ping >/dev/null 2>&1
}log_success_msg () {echo " * $@" || true
}log_failure_msg () {if log_use_fancy_output; thenRED=`$TPUT setaf 1`NORMAL=`$TPUT op`echo " $RED*$NORMAL $@" || trueelseecho " * $@" || truefi
}log_warning_msg () {if log_use_fancy_output; thenYELLOW=`$TPUT setaf 3`NORMAL=`$TPUT op`echo " $YELLOW*$NORMAL $@" || trueelseecho " * $@" || truefi
}log_begin_msg () {log_daemon_msg "$1"
}log_daemon_msg () {if [ -z "$1" ]; thenreturn 1fiif log_use_fancy_output && $TPUT xenl >/dev/null 2>&1; thenCOLS=`$TPUT cols`if [ "$COLS" ] && [ "$COLS" -gt 6 ]; thenCOL=`$EXPR $COLS - 7`elseCOLS=80COL=73fiif log_use_plymouth; then# If plymouth is running, don't output anything at this time# to avoid buffering problems (LP: #752393)if [ -z "$LOG_DAEMON_MSG" ]; thenLOG_DAEMON_MSG=$*returnfifi# We leave the cursor `hanging' about-to-wrap (see terminfo(5)# xenl, which is approximately right). That way if the script# prints anything then we will be on the next line and not# overwrite part of the message.# Previous versions of this code attempted to colour-code the# asterisk but this can't be done reliably because in practice# init scripts sometimes print messages even when they succeed# and we won't be able to reliably know where the colourful# asterisk ought to go.printf " * $* " || true# Enough trailing spaces for ` [fail]' to fit in; if the message# is too long it wraps here rather than later, which is what we# want.$TPUT hpa `$EXPR $COLS - 1` || trueprintf ' ' || trueelseecho " * $@" || trueCOL=fi
}log_progress_msg () {:
}log_end_msg () {if [ -z "$1" ]; thenreturn 1fiif [ "$COL" ] && [ -x "$TPUT" ]; then# If plymouth is running, print previously stored output# to avoid buffering problems (LP: #752393)if log_use_plymouth; thenif [ -n "$LOG_DAEMON_MSG" ]; thenlog_daemon_msg $LOG_DAEMON_MSGLOG_DAEMON_MSG=""fifiprintf "\\r" || true$TPUT hpa $COLif [ "$1" -eq 0 ]; thenecho "[ OK ]" || trueelseprintf '[' || true$TPUT setaf 1 || true # redprintf fail || true$TPUT op || true # normalecho ']' || truefielseif [ "$1" -eq 0 ]; thenecho " ...done." || trueelseecho " ...fail!" || truefifireturn $1
}log_action_msg () {echo " * $@" || true
}log_action_begin_msg () {log_daemon_msg "$@..." || true
}log_action_cont_msg () {log_daemon_msg "$@..." || true
}log_action_end_msg () {# In the future this may do something with $2 as well.log_end_msg "$1" || true
}就分析到这里吧，不再深入了。