Service命令在不同的Linux發(fā)行版中都有不同的實現(xiàn)骚灸，并且同一發(fā)行版不同的版本號之間功能也不盡相同
但無論怎么變化虱朵，Service命令永遠都只是一組腳本
下面對比的是 CentOS6.5蓖康、CentOS8.3以及Ubuntu20.04蓉坎，Service命令的代碼變化
//CentOS6.5 位于/sbin/service
#!/bin/sh
. /etc/init.d/functions
VERSION="$(basename $0) ver. 0.91"
USAGE="Usage: $(basename $0) < option > | --status-all | \
[ service_name [ command | --full-restart ] ]"
SERVICE=
SERVICEDIR="/etc/init.d"
OPTIONS=
if [ $# -eq 0 ]; then
echo "${USAGE}" >&2
exit 1
fi
cd /
while [ $# -gt 0 ]; do
case "${1}" in
--help | -h | --h* )
echo "${USAGE}" >&2
exit 0
;;
--version | -V )
echo "${VERSION}" >&2
exit 0
;;
*)
if [ -z "${SERVICE}" -a $# -eq 1 -a "${1}" = "--status-all" ]; then
cd ${SERVICEDIR}
for SERVICE in * ; do
case "${SERVICE}" in
functions | halt | killall | single| linuxconf| kudzu)
;;
*)
if ! is_ignored_file "${SERVICE}" \
&& [ -x "${SERVICEDIR}/${SERVICE}" ]; then
env -i PATH="$PATH" TERM="$TERM" "${SERVICEDIR}/${SERVICE}" status
fi
;;
esac
done
exit 0
elif [ $# -eq 2 -a "${2}" = "--full-restart" ]; then
SERVICE="${1}"
if [ -x "${SERVICEDIR}/${SERVICE}" ]; then
env -i PATH="$PATH" TERM="$TERM" "${SERVICEDIR}/${SERVICE}" stop
env -i PATH="$PATH" TERM="$TERM" "${SERVICEDIR}/${SERVICE}" start
exit $?
fi
elif [ -z "${SERVICE}" ]; then
SERVICE="${1}"
else
OPTIONS="${OPTIONS} ${1}"
fi
shift
;;
esac
done
if [ -f "${SERVICEDIR}/${SERVICE}" ]; then
env -i PATH="$PATH" TERM="$TERM" "${SERVICEDIR}/${SERVICE}" ${OPTIONS}
else
echo $"${SERVICE}: unrecognized service" >&2
exit 1
fi
//CentOS8.3 位于/sbin/service 實際鏈接指向 /usr/sbin/service
#!/bin/bash
. /etc/init.d/functions
VERSION="$(basename $0) ver. 1.1"
USAGE="Usage: $(basename $0) < option > | --status-all | \
[ service_name [ command | --full-restart ] ]"
SERVICEDIR="/etc/init.d"
ACTIONDIR="/usr/libexec/initscripts/legacy-actions"
SERVICE=
ACTION=
OPTIONS=
if [ $# -eq 0 ]; then
echo "${USAGE}" >&2
exit 1
fi
cd /
while [ $# -gt 0 ]; do
case "${1}" in
--help | -h | --h* )
echo "${USAGE}" >&2
exit 0
;;
--version | -V )
echo "${VERSION}" >&2
exit 0
;;
--ignore-dependencies)
export SYSTEMCTL_IGNORE_DEPENDENCIES=1
shift
;;
--skip-redirect)
export SYSTEMCTL_SKIP_REDIRECT=1
shift
;;
*)
if [ -z "${SERVICE}" -a $# -eq 1 -a "${1}" = "--status-all" ]; then
cd ${SERVICEDIR}
for SERVICE in * ; do
case "${SERVICE}" in
functions | halt | killall | single| linuxconf| kudzu)
;;
*)
if ! is_ignored_file "${SERVICE}" \
&& [ -x "${SERVICEDIR}/${SERVICE}" ]; then
env -i PATH="$PATH" TERM="$TERM" "${SERVICEDIR}/${SERVICE}" status
fi
;;
esac
done
exit 0
elif [ $# -eq 2 -a "${2}" = "--full-restart" ]; then
SERVICE="${1}"
if [ -x "${SERVICEDIR}/${SERVICE}" ]; then
env -i PATH="$PATH" TERM="$TERM" "${SERVICEDIR}/${SERVICE}" stop
env -i PATH="$PATH" TERM="$TERM" "${SERVICEDIR}/${SERVICE}" start
exit $?
fi
elif [ -z "${SERVICE}" ]; then
SERVICE="${1}"
elif [ -z "${ACTION}" ]; then
ACTION="${1}"
else
OPTIONS="${OPTIONS} ${1}"
fi
shift
;;
esac
done
if [ -f "${SERVICEDIR}/${SERVICE}" ]; then
# LSB daemons that dies abnormally in systemd looks alive in systemd's eyes due to RemainAfterExit=yes
# lets reap them before next start
if [ "${ACTION}" = "start" ] && \
systemctl show -p ActiveState ${SERVICE}.service | grep -q '=active$' && \
systemctl show -p SubState ${SERVICE}.service | grep -q '=exited$' ; then
/bin/systemctl stop ${SERVICE}.service
fi
# Workaround to be able to "stop" network.service when it's in inactive state using service instead of systemctl
# Useful for manual testing of network
if [ "${SERVICE}" = 'network' ] && [ "${ACTION}" = 'stop' ] && \
[ "$(systemctl show -p ActiveState network.service --value)" = 'inactive' ] && \
[ "$(systemctl show -p SourcePath network.service --value)" = '/etc/rc.d/init.d/network' ]; then
export SYSTEMCTL_SKIP_REDIRECT=1
fi
env -i PATH="$PATH" TERM="$TERM" SYSTEMCTL_IGNORE_DEPENDENCIES=${SYSTEMCTL_IGNORE_DEPENDENCIES} SYSTEMCTL_SKIP_REDIRECT=${SYSTEMCTL_SKIP_REDIRECT} "${SERVICEDIR}/${SERVICE}" ${ACTION} ${OPTIONS}
elif [ -n "${ACTION}" ] && [ -x "${ACTIONDIR}/${SERVICE}/${ACTION}" ]; then
env -i PATH="$PATH" TERM="$TERM" SYSTEMCTL_IGNORE_DEPENDENCIES=${SYSTEMCTL_IGNORE_DEPENDENCIES} SYSTEMCTL_SKIP_REDIRECT=${SYSTEMCTL_SKIP_REDIRECT} "${ACTIONDIR}/${SERVICE}/${ACTION}" ${OPTIONS}
elif `echo $ACTION | grep -Eqw "start|stop|restart|try-restart|reload|force-reload|status|condrestart"` ; then
SERVICE_MANGLED=$(/usr/bin/systemd-escape --mangle ${SERVICE})
echo $"Redirecting to /bin/systemctl ${ACTION}${OPTIONS:+ }${OPTIONS} ${SERVICE_MANGLED}" >&2
exec /bin/systemctl ${ACTION} ${OPTIONS} ${SERVICE_MANGLED}
else
echo $"The service command supports only basic LSB actions (start, stop, restart, try-restart, reload, force-reload, status). For other actions, please try to use systemctl." >&2
exit 2
fi
//Ubuntu20.04 位于/usr/sbin/service
#!/bin/bash
###########################################################################
# /usr/bin/service
#
# A convenient wrapper for the /etc/init.d init scripts.
#
# This script is a modified version of the /sbin/service utility found on
# Red Hat/Fedora systems (licensed GPLv2+).
#
# Copyright (C) 2006 Red Hat, Inc. All rights reserved.
# Copyright (C) 2008 Canonical Ltd.
# * August 2008 - Dustin Kirkland <kirkland@canonical.com>
# Copyright (C) 2013 Michael Stapelberg <stapelberg@debian.org>
#
# This program is free software; you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation; either version 2 of the License, or
# (at your option) any later version.
#
# This program 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 General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program; if not, write to the Free Software
# Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
#
# On Debian GNU/Linux systems, the complete text of the GNU General
# Public License can be found in `/usr/share/common-licenses/GPL-2'.
###########################################################################
is_ignored_file() {
case "$1" in
skeleton | README | *.dpkg-dist | *.dpkg-old | rc | rcS | single | reboot | bootclean.sh)
return 0
;;
esac
return 1
}
VERSION="`basename $0` ver. 1.57"
USAGE="Usage: `basename $0` < option > | --status-all | \
[ service_name [ command | --full-restart ] ]"
SERVICE=
ACTION=
SERVICEDIR="/etc/init.d"
OPTIONS=
is_systemd=
if [ $# -eq 0 ]; then
echo "${USAGE}" >&2
exit 1
fi
if [ -d /run/systemd/system ]; then
is_systemd=1
fi
cd /
while [ $# -gt 0 ]; do
case "${1}" in
--help | -h | --h* )
echo "${USAGE}" >&2
exit 0
;;
--version | -V )
echo "${VERSION}" >&2
exit 0
;;
*)
if [ -z "${SERVICE}" -a $# -eq 1 -a "${1}" = "--status-all" ]; then
cd ${SERVICEDIR}
for SERVICE in * ; do
case "${SERVICE}" in
functions | halt | killall | single| linuxconf| kudzu)
;;
*)
if ! is_ignored_file "${SERVICE}" \
&& [ -x "${SERVICEDIR}/${SERVICE}" ]; then
out=$(env -i LANG="$LANG" LANGUAGE="$LANGUAGE" LC_CTYPE="$LC_CTYPE" LC_NUMERIC="$LC_NUMERIC" LC_TIME="$LC_TIME" LC_COLLATE="$LC_COLLATE" LC_MONETARY="$LC_MONETARY" LC_MESSAGES="$LC_MESSAGES" LC_PAPER="$LC_PAPER" LC_NAME="$LC_NAME" LC_ADDRESS="$LC_ADDRESS" LC_TELEPHONE="$LC_TELEPHONE" LC_MEASUREMENT="$LC_MEASUREMENT" LC_IDENTIFICATION="$LC_IDENTIFICATION" LC_ALL="$LC_ALL" PATH="$PATH" TERM="$TERM" "$SERVICEDIR/$SERVICE" status 2>&1)
retval=$?
if echo "$out" | egrep -iq "usage:"; then
#printf " %s %-60s %s\n" "[?]" "$SERVICE:" "unknown" 1>&2
echo " [ ? ] $SERVICE" 1>&2
continue
else
if [ "$retval" = "0" -a -n "$out" ]; then
#printf " %s %-60s %s\n" "[+]" "$SERVICE:" "running"
echo " [ + ] $SERVICE"
continue
else
#printf " %s %-60s %s\n" "[-]" "$SERVICE:" "NOT running"
echo " [ - ] $SERVICE"
continue
fi
fi
#env -i LANG="$LANG" LANGUAGE="$LANGUAGE" LC_CTYPE="$LC_CTYPE" LC_NUMERIC="$LC_NUMERIC" LC_TIME="$LC_TIME" LC_COLLATE="$LC_COLLATE" LC_MONETARY="$LC_MONETARY" LC_MESSAGES="$LC_MESSAGES" LC_PAPER="$LC_PAPER" LC_NAME="$LC_NAME" LC_ADDRESS="$LC_ADDRESS" LC_TELEPHONE="$LC_TELEPHONE" LC_MEASUREMENT="$LC_MEASUREMENT" LC_IDENTIFICATION="$LC_IDENTIFICATION" LC_ALL="$LC_ALL" PATH="$PATH" TERM="$TERM" "$SERVICEDIR/$SERVICE" status
fi
;;
esac
done
exit 0
elif [ $# -eq 2 -a "${2}" = "--full-restart" ]; then
SERVICE="${1}"
# On systems using systemd, we just perform a normal restart:
# A restart with systemd is already a full restart.
if [ -n "$is_systemd" ]; then
ACTION="restart"
else
if [ -x "${SERVICEDIR}/${SERVICE}" ]; then
env -i LANG="$LANG" LANGUAGE="$LANGUAGE" LC_CTYPE="$LC_CTYPE" LC_NUMERIC="$LC_NUMERIC" LC_TIME="$LC_TIME" LC_COLLATE="$LC_COLLATE" LC_MONETARY="$LC_MONETARY" LC_MESSAGES="$LC_MESSAGES" LC_PAPER="$LC_PAPER" LC_NAME="$LC_NAME" LC_ADDRESS="$LC_ADDRESS" LC_TELEPHONE="$LC_TELEPHONE" LC_MEASUREMENT="$LC_MEASUREMENT" LC_IDENTIFICATION="$LC_IDENTIFICATION" LC_ALL="$LC_ALL" PATH="$PATH" TERM="$TERM" "$SERVICEDIR/$SERVICE" stop
env -i LANG="$LANG" LANGUAGE="$LANGUAGE" LC_CTYPE="$LC_CTYPE" LC_NUMERIC="$LC_NUMERIC" LC_TIME="$LC_TIME" LC_COLLATE="$LC_COLLATE" LC_MONETARY="$LC_MONETARY" LC_MESSAGES="$LC_MESSAGES" LC_PAPER="$LC_PAPER" LC_NAME="$LC_NAME" LC_ADDRESS="$LC_ADDRESS" LC_TELEPHONE="$LC_TELEPHONE" LC_MEASUREMENT="$LC_MEASUREMENT" LC_IDENTIFICATION="$LC_IDENTIFICATION" LC_ALL="$LC_ALL" PATH="$PATH" TERM="$TERM" "$SERVICEDIR/$SERVICE" start
exit $?
fi
fi
elif [ -z "${SERVICE}" ]; then
SERVICE="${1}"
elif [ -z "${ACTION}" ]; then
ACTION="${1}"
else
OPTIONS="${OPTIONS} ${1}"
fi
shift
;;
esac
done
run_via_sysvinit() {
# Otherwise, use the traditional sysvinit
if [ -x "${SERVICEDIR}/${SERVICE}" ]; then
exec env -i LANG="$LANG" LANGUAGE="$LANGUAGE" LC_CTYPE="$LC_CTYPE" LC_NUMERIC="$LC_NUMERIC" LC_TIME="$LC_TIME" LC_COLLATE="$LC_COLLATE" LC_MONETARY="$LC_MONETARY" LC_MESSAGES="$LC_MESSAGES" LC_PAPER="$LC_PAPER" LC_NAME="$LC_NAME" LC_ADDRESS="$LC_ADDRESS" LC_TELEPHONE="$LC_TELEPHONE" LC_MEASUREMENT="$LC_MEASUREMENT" LC_IDENTIFICATION="$LC_IDENTIFICATION" LC_ALL="$LC_ALL" PATH="$PATH" TERM="$TERM" "$SERVICEDIR/$SERVICE" ${ACTION} ${OPTIONS}
else
echo "${SERVICE}: unrecognized service" >&2
exit 1
fi
}
update_openrc_started_symlinks() {
# maintain the symlinks of /run/openrc/started so that
# rc-status works with the service command as well
if [ -d /run/openrc/started ] ; then
case "${ACTION}" in
start)
if [ ! -h /run/openrc/started/$SERVICE ] ; then
ln -s $SERVICEDIR/$SERVICE /run/openrc/started/$SERVICE || true
fi
;;
stop)
rm /run/openrc/started/$SERVICE || true
;;
esac
fi
}
# When this machine is running systemd, standard service calls are turned into
# systemctl calls.
if [ -n "$is_systemd" ]
then
UNIT="${SERVICE%.sh}.service"
# avoid deadlocks during bootup and shutdown from units/hooks
# which call "invoke-rc.d service reload" and similar, since
# the synchronous wait plus systemd's normal behaviour of
# transactionally processing all dependencies first easily
# causes dependency loops
if ! systemctl --quiet is-active multi-user.target; then
sctl_args="--job-mode=ignore-dependencies"
fi
case "${ACTION}" in
restart|status|try-restart)
exec systemctl $sctl_args ${ACTION} ${UNIT}
;;
start|stop)
# Follow the principle of least surprise for SysV people:
# When running "service foo stop" and foo happens to be a service that
# has one or more .socket files, we also stop the .socket units.
# Users who need more control will use systemctl directly.
for unit in $(systemctl list-unit-files --full --type=socket 2>/dev/null | sed -ne 's/\.socket\s*[a-z]*\s*$/.socket/p'); do
if [ "$(systemctl -p Triggers show $unit)" = "Triggers=${UNIT}" ]; then
systemctl $sctl_args ${ACTION} $unit
fi
done
exec systemctl $sctl_args ${ACTION} ${UNIT}
;;
reload)
_canreload="$(systemctl -p CanReload show ${UNIT} 2>/dev/null)"
if [ "$_canreload" = "CanReload=no" ]; then
# The reload action falls back to the sysv init script just in case
# the systemd service file does not (yet) support reload for a
# specific service.
run_via_sysvinit
else
exec systemctl $sctl_args reload "${UNIT}"
fi
;;
force-stop)
exec systemctl --signal=KILL kill "${UNIT}"
;;
force-reload)
_canreload="$(systemctl -p CanReload show ${UNIT} 2>/dev/null)"
if [ "$_canreload" = "CanReload=no" ]; then
exec systemctl $sctl_args restart "${UNIT}"
else
exec systemctl $sctl_args reload "${UNIT}"
fi
;;
*)
# We try to run non-standard actions by running
# the init script directly.
run_via_sysvinit
;;
esac
fi
update_openrc_started_symlinks
run_via_sysvinit
可以看得出肿孵，無論是Red Hat系還是Debian系唠粥，service命令的前半部分的邏輯都是十分相似的优炬，不同的是后面部分，CentOS8.3在后面加上了 systemctl 命令的邏輯厅贪，這個命令在 CentOS6.5中是沒有的蠢护，而 Ubuntu的后面部分也是自己特色的實現(xiàn)，不過這些這里暫且不表养涮，這里只淺析一下 service --status-all 這個參數(shù)在不同發(fā)行版中的不同表現(xiàn)
if [ -z "${SERVICE}" -a $# -eq 1 -a "${1}" = "--status-all" ]; then
cd ${SERVICEDIR}
for SERVICE in * ; do
case "${SERVICE}" in
functions | halt | killall | single| linuxconf| kudzu)
;;
*)
if ! is_ignored_file "${SERVICE}" \
&& [ -x "${SERVICEDIR}/${SERVICE}" ]; then
env -i PATH="$PATH" TERM="$TERM" "${SERVICEDIR}/${SERVICE}" status
fi
;;
esac
done
exit 0
......
從這一段代碼可以看出葵硕，service加上--status-all參數(shù)后，就會將 /etc/init.d/ 目錄下的所有腳本帶上 status 參數(shù)循環(huán)執(zhí)行一遍然后再對輸出進行過濾格式化贯吓，但詭異的是懈凹，CentOS8.3 把 /etc/init.d/ 目錄下的所有應用啟動腳本全部刪除了，空空如也
沒有啟動腳本了
所以在 CentOS8.3 中悄谐，執(zhí)行 service --status-all 是沒有任何輸出的介评，不信大家可以試一下，這時如果想得知哪個服務是否安裝了爬舰，只能使用 ps -aux 查看進程或者使用 netstat -tnlp 查看某個端口了们陆，又或者使用包管理工具 rpm 來查看
CentOS6.5 和 Ubuntu20.04下這個命令是沒有問題的
root@localhost:~# service --status-all
[ + ] aegis
[ + ] apache2
[ - ] apache-htcacheclean
[ + ] apparmor
[ + ] atd
[ + ] chrony
[ - ] console-setup.sh
[ + ] cron
[ + ] dbus
[ - ] fio
[ + ] grub-common
[ - ] hwclock.sh
[ - ] irqbalance
[ - ] keyboard-setup.sh
[ + ] kmod
[ - ] nginx
[ - ] ntp
[ - ] plymouth
[ - ] plymouth-log
[ + ] procps
....
Ubuntu20.04
當系統(tǒng)引入 systemctl 命令之后，service本質上就是對 systemctl 進行了一次包裝情屹，實際都是執(zhí)行這個命令來調用.service配置文件（位于 /usr/lib/systemd/system ）進行控制操作坪仇，這一點 Ubuntu20.04 和 CentOS8.3 很像，不像 CentOS6.5 垃你，腳本中是直接與應用二進制文件打交道椅文。
所以對服務的操控可以有兩種寫法(后者直接使用了 systemctl 命令調用 .service 配置文件)
- service apache2 start
2.systemctl start apache2.service
service的控制單元是一個個的 .service 配置文件，每個 .service 文件對應一個服務的控制操作惜颇，.service文件的書寫有一定的規(guī)范皆刺，下面是 Ubuntu20.04下 apache2.service 的配置內容( CentOS 中是 httpd.service )
[Unit]
Description=The Apache HTTP Server
After=network.target remote-fs.target nss-lookup.target
Documentation=https://httpd.apache.org/docs/2.4/
[Service]
Type=forking
Environment=APACHE_STARTED_BY_SYSTEMD=true
ExecStart=/usr/sbin/apachectl start
ExecStop=/usr/sbin/apachectl stop
ExecReload=/usr/sbin/apachectl graceful
PrivateTmp=true
Restart=on-abort
[Install]
WantedBy=multi-user.target
可以看出，service 配置文件才是真正與二進制文件進行關聯(lián)的
再來看看 /etc/init.d/apache2 腳本
再次說明凌摄，CentOS8.3 是沒有這個腳本的羡蛾，而 CentOS6.5 是直接與二進制文件進行交互，這里就以 Ubuntu20.04 進行說明
前面說過望伦，service --status-all 實際上是將這個目錄下的腳本全部循環(huán)加上 status 參數(shù)執(zhí)行一遍林说，也就是說
/etc/init.d/apache2 status 這條命令是會被執(zhí)行的
root@localhost:~# /etc/init.d/apache2 status
● apache2.service - The Apache HTTP Server
Loaded: loaded (/lib/systemd/system/apache2.service; enabled; vendor preset: enabled)
Active: active (running) since Mon 2021-06-28 13:49:56 CST; 20h ago
Docs: https://httpd.apache.org/docs/2.4/
Process: 6856 ExecReload=/usr/sbin/apachectl graceful (code=exited, status=0/SUCCESS)
Main PID: 2003 (apache2)
Tasks: 55 (limit: 2193)
Memory: 8.4M
CGroup: /system.slice/apache2.service
├─2003 /usr/sbin/apache2 -k start
├─6860 /usr/sbin/apache2 -k start
└─6861 /usr/sbin/apache2 -k start
Jun 28 13:49:56 localhost systemd[1]: Starting The Apache HTTP Server...
Jun 28 13:49:56 localhost apachectl[2002]: AH00558: apache2: Could not reliably determine t…ssage
Jun 28 13:49:56 localhost systemd[1]: Started The Apache HTTP Server.
Jun 29 00:01:00 localhost systemd[1]: Reloading The Apache HTTP Server.
Jun 29 00:01:00 localhost apachectl[6859]: AH00558: apache2: Could not reliably determine t…ssage
Jun 29 00:01:00 localhost systemd[1]: Reloaded The Apache HTTP Server.
Hint: Some lines were ellipsized, use -l to show in full.
以上是直接執(zhí)行 /etc/init.d/apache2 status 的輸出結果，但為何執(zhí)行 service --status-all 又變成了列表形式的呢屯伞，那時因為對輸出結果進行了一系列變換格式化操作，現(xiàn)在我們看下為何 /etc/init.d/apache2 status 的輸出結果是這樣豪直，本質上是哪部分代碼被執(zhí)行了
用文本編輯器打開 /etc/init.d/apache2 腳本劣摇，大概在 53 行處
. /lib/lsb/init-functions //實際上指向 /usr/lib/lsb/init-functions
輸出的功能性代碼就在這個引入腳本里，再打開這個腳本弓乙，在末尾處
for hook in $(run-parts --lsbsysinit --list /lib/lsb/init-functions.d 2>/dev/null); do
[ -r $hook ] && . $hook || true
done
又是循環(huán)執(zhí)行了腳本末融，再次打開 /lib/lsb/init-functions.d （實際指向是 /usr/lib/lsb/init-functions.d ）
init-functions.d
這里面的腳本都會執(zhí)行一遍钧惧，重點就是那個 systemd ，用文本編輯器打開勾习，最后幾行代碼
case "$argument" in
start|stop|restart|reload|force-reload|try-restart|status)
systemctl_redirect $executable $argument
exit $?
;;
esac
systemctl_redirect 這個函數(shù)的實現(xiàn)在 systemd 文本的前半部分
systemctl_redirect () {
local s
local rc
local prog=${1##*/}
local command=$2
case "$command" in
start)
s="Starting $prog (via systemctl)"
;;
stop)
s="Stopping $prog (via systemctl)"
;;
reload|force-reload)
s="Reloading $prog configuration (via systemctl)"
;;
try-restart)
s="Restarting $prog if running (via systemctl)"
;;
restart)
s="Restarting $prog (via systemctl)"
;;
esac
service="${prog%.sh}.service"
# avoid deadlocks during bootup and shutdown from units/hooks
# which call "invoke-rc.d service reload" and similar, since
# the synchronous wait plus systemd's normal behaviour of
# transactionally processing all dependencies first easily
# causes dependency loops
if ! OUT=$(systemctl is-system-running 2>/dev/null) && [ "$OUT" != "degraded" ]; then
sctl_args="--job-mode=ignore-dependencies"
fi
[ "$command" = status ] || log_daemon_msg "$s" "$service"
/bin/systemctl --no-pager $sctl_args $command "$service" //這行才是重點
rc=$?
[ "$command" = status ] || log_end_msg $rc
return $rc
}
/bin/systemctl --no-pager $sctl_args $command "$service"這一行才是重點浓瞪，大概在全文的 82 行左右
如果把里面的變量替換展開，最后執(zhí)行的命令行大概就是這樣
/bin/systemctl --no-pager status apache2.service
直接運行這條命令巧婶，可以得到和 /etc/init.d/apache2 status 一樣的輸出
結論
沒想到 service --staus-all 最后還是依賴于 systemctl 這個命令乾颁，不過 /etc/init.d 里面大量的腳本只是為了使 service --staus-all 這條命令有效，是不是有點浪費艺栈，如果像 CentOS8.3 那樣直接刪掉英岭，是不是更顯得簡潔，你覺得呢湿右？
