如何檢視 Linux 中所有正在運作的服務

有許多方法和工具可以檢視 Linux 中所有正在運作的服務。大多數管理者會在 System V（SysV）初始化系統中使用 service service-name status 或 /etc/init.d/service-name status，而在 systemd 初始化系統中使用 systemctl status service-name。

以上指令可以清楚地顯示該服務是否在伺服器上運作，這也是每個 Linux 管理者都該知道的非常簡單和基礎的指令。

如果你對系統環境并不熟悉，也不清楚系統在運作哪些服務，你會如何檢查？

是的，我們的确有必要這樣檢查一下。這将有助于我們了解系統上運作了什麼服務，以及哪些是必要的、哪些需要被禁用。

init（初始化initialization的簡稱）是在系統啟動期間運作的第一個程序。init 是一個守護程序，它将持續運作直至關機。

大多數 Linux 發行版都使用如下的初始化系統之一：

System V 是更老的初始化系統

Upstart 是一個基于事件的傳統的初始化系統的替代品

systemd 是新的初始化系統，它已經被大多數最新的 Linux 發行版所采用

什麼是 System V（SysV）

SysV（意即 System V） 初始化系統是早期傳統的初始化系統和系統管理器。由于 sysVinit 系統上一些長期懸而未決的問題，大多數最新的發行版都适用于 systemd 系統。

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什麼是 Upstart 初始化系統

Upstart 是一個基于事件的 /sbin/init 的替代品，它控制在啟動時的任務和服務的開始，在關機時停止它們，并在系統運作時監控它們。

它最初是為 Ubuntu 發行版開發的，但其是以适合所有 Linux 發行版的開發為目标的，以替換過時的 System-V 初始化系統。

什麼是 systemd

systemd 是一個新的初始化系統以及系統管理器，它已成為大多數 Linux 發行版中非常流行且廣泛适應的新的标準初始化系統。systemctl 是一個 systemd 管理工具，它可以幫助我們管理 systemd 系統。

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方法一：如何在 System V（SysV）系統中檢視運作的服務

以下指令可以幫助我們列出 System V（SysV） 系統中所有正在運作的服務。

如果服務很多，我建議使用檔案檢視指令，如 less、more 等，以便得到清晰的結果。

service --status-all

或

service --status-all | more

service --status-all | less

abrt-ccpp hook is installed

abrtd (pid 2131) is running...

abrt-dump-oops is stopped

acpid (pid 1958) is running...

atd (pid 2164) is running...

auditd (pid 1731) is running...

Frequency scaling enabled using ondemand governor

crond (pid 2153) is running...

hald (pid 1967) is running...

htcacheclean is stopped

httpd is stopped

Table: filter

Chain INPUT (policy ACCEPT)

num target prot opt source destination

1 ACCEPT all ::/0 ::/0 state RELATED,ESTABLISHED

2 ACCEPT icmpv6 ::/0 ::/0

3 ACCEPT all ::/0 ::/0

4 ACCEPT tcp ::/0 ::/0 state NEW tcp dpt:80

5 ACCEPT tcp ::/0 ::/0 state NEW tcp dpt:21

6 ACCEPT tcp ::/0 ::/0 state NEW tcp dpt:22

7 ACCEPT tcp ::/0 ::/0 state NEW tcp dpt:25

8 ACCEPT tcp ::/0 ::/0 state NEW tcp dpt:2082

9 ACCEPT tcp ::/0 ::/0 state NEW tcp dpt:2086

10 ACCEPT tcp ::/0 ::/0 state NEW tcp dpt:2083

11 ACCEPT tcp ::/0 ::/0 state NEW tcp dpt:2087

12 ACCEPT tcp ::/0 ::/0 state NEW tcp dpt:10000

13 REJECT all ::/0 ::/0 reject-with icmp6-adm-prohibited

Chain FORWARD (policy ACCEPT)

1 REJECT all ::/0 ::/0 reject-with icmp6-adm-prohibited

Chain OUTPUT (policy ACCEPT)

iptables: Firewall is not running.

irqbalance (pid 1826) is running...

Kdump is operational

lvmetad is stopped

mdmonitor is stopped

messagebus (pid 1929) is running...

SUCCESS! MySQL running (24376)

rndc: neither /etc/rndc.conf nor /etc/rndc.key was found

named is stopped

netconsole module not loaded

Usage: startup.sh { start | stop }

Configured devices:

lo eth0 eth1

Currently active devices:

lo eth0

ntpd is stopped

portreserve (pid 1749) is running...

master (pid 2107) is running...

Process accounting is disabled.

quota_nld is stopped

rdisc is stopped

rngd is stopped

rpcbind (pid 1840) is running...

rsyslogd (pid 1756) is running...

sandbox is stopped

saslauthd is stopped

smartd is stopped

openssh-daemon (pid 9859) is running...

svnserve is stopped

vsftpd (pid 4008) is running...

xinetd (pid 2031) is running...

zabbix_agentd (pid 2150 2149 2148 2147 2146 2140) is running...

執行以下指令，可以隻檢視正在運作的服務：

service --status-all | grep running

crond (pid 535) is running...

httpd (pid 627) is running...

mysqld (pid 911) is running...

rsyslogd (pid 449) is running...

saslauthd (pid 492) is running...

sendmail (pid 509) is running...

sm-client (pid 519) is running...

openssh-daemon (pid 478) is running...

xinetd (pid 485) is running...

運作以下指令以檢視指定服務的狀态：

service --status-all | grep httpd

或者，使用以下指令也可以檢視指定服務的狀态：

service httpd status

使用以下指令檢視系統啟動時哪些服務會被啟用：

chkconfig --list

crond 0:off 1:off 2:on 3:on 4:on 5:on 6:off

htcacheclean 0:off 1:off 2:off 3:off 4:off 5:off 6:off

httpd 0:off 1:off 2:off 3:on 4:off 5:off 6:off

ip6tables 0:off 1:off 2:on 3:off 4:on 5:on 6:off

iptables 0:off 1:off 2:on 3:on 4:on 5:on 6:off

modules_dep 0:off 1:off 2:on 3:on 4:on 5:on 6:off

mysqld 0:off 1:off 2:on 3:on 4:on 5:on 6:off

named 0:off 1:off 2:off 3:off 4:off 5:off 6:off

netconsole 0:off 1:off 2:off 3:off 4:off 5:off 6:off

netfs 0:off 1:off 2:off 3:off 4:on 5:on 6:off

network 0:off 1:off 2:on 3:on 4:on 5:on 6:off

nmb 0:off 1:off 2:off 3:off 4:off 5:off 6:off

nscd 0:off 1:off 2:off 3:off 4:off 5:off 6:off

portreserve 0:off 1:off 2:on 3:off 4:on 5:on 6:off

quota_nld 0:off 1:off 2:off 3:off 4:off 5:off 6:off

rdisc 0:off 1:off 2:off 3:off 4:off 5:off 6:off

restorecond 0:off 1:off 2:off 3:off 4:off 5:off 6:off

rpcbind 0:off 1:off 2:on 3:off 4:on 5:on 6:off

rsyslog 0:off 1:off 2:on 3:on 4:on 5:on 6:off

saslauthd 0:off 1:off 2:off 3:on 4:off 5:off 6:off

sendmail 0:off 1:off 2:on 3:on 4:on 5:on 6:off

smb 0:off 1:off 2:off 3:off 4:off 5:off 6:off

snmpd 0:off 1:off 2:off 3:off 4:off 5:off 6:off

snmptrapd 0:off 1:off 2:off 3:off 4:off 5:off 6:off

sshd 0:off 1:off 2:on 3:on 4:on 5:on 6:off

udev-post 0:off 1:on 2:on 3:off 4:on 5:on 6:off

winbind 0:off 1:off 2:off 3:off 4:off 5:off 6:off

xinetd 0:off 1:off 2:off 3:on 4:on 5:on 6:off

xinetd based services:

chargen-dgram: off

chargen-stream: off

daytime-dgram: off

daytime-stream: off

discard-dgram: off

discard-stream: off

echo-dgram: off

echo-stream: off

finger: off

ntalk: off

rsync: off

talk: off

tcpmux-server: off

time-dgram: off

time-stream: off

方法二：如何在 System V（SysV）系統中檢視運作的服務

另外一種在 Linux 系統上列出運作的服務的方法是使用 initctl 指令：

initctl list

rc stop/waiting

tty (/dev/tty3) start/running, process 1740

tty (/dev/tty2) start/running, process 1738

tty (/dev/tty1) start/running, process 1736

tty (/dev/tty6) start/running, process 1746

tty (/dev/tty5) start/running, process 1744

tty (/dev/tty4) start/running, process 1742

plymouth-shutdown stop/waiting

control-alt-delete stop/waiting

rcS-emergency stop/waiting

readahead-collector stop/waiting

kexec-disable stop/waiting

quit-plymouth stop/waiting

rcS stop/waiting

prefdm stop/waiting

init-system-dbus stop/waiting

ck-log-system-restart stop/waiting

readahead stop/waiting

ck-log-system-start stop/waiting

splash-manager stop/waiting

start-ttys stop/waiting

readahead-disable-services stop/waiting

ck-log-system-stop stop/waiting

rcS-sulogin stop/waiting

serial stop/waiting

方法三：如何在 systemd 系統中檢視運作的服務

以下指令幫助我們列出 systemd 系統中所有服務：

systemctl

UNIT LOAD ACTIVE SUB DESCRIPTION

sys-devices-virtual-block-loop0.device loaded active plugged /sys/devices/virtual/block/loop0

sys-devices-virtual-block-loop1.device loaded active plugged /sys/devices/virtual/block/loop1

sys-devices-virtual-block-loop2.device loaded active plugged /sys/devices/virtual/block/loop2

sys-devices-virtual-block-loop3.device loaded active plugged /sys/devices/virtual/block/loop3

sys-devices-virtual-block-loop4.device loaded active plugged /sys/devices/virtual/block/loop4

sys-devices-virtual-misc-rfkill.device loaded active plugged /sys/devices/virtual/misc/rfkill

sys-devices-virtual-tty-ttyprintk.device loaded active plugged /sys/devices/virtual/tty/ttyprintk

sys-module-fuse.device loaded active plugged /sys/module/fuse

sys-subsystem-net-devices-enp0s3.device loaded active plugged 82540EM Gigabit Ethernet Controller (PRO/1000 MT Desktop Adapter)

-.mount loaded active mounted Root Mount

dev-hugepages.mount loaded active mounted Huge Pages File System

dev-mqueue.mount loaded active mounted POSIX Message Queue File System

run-user-1000-gvfs.mount loaded active mounted /run/user/1000/gvfs

run-user-1000.mount loaded active mounted /run/user/1000

snap-core-3887.mount loaded active mounted Mount unit for core

snap-core-4017.mount loaded active mounted Mount unit for core

snap-core-4110.mount loaded active mounted Mount unit for core

snap-gping-13.mount loaded active mounted Mount unit for gping

snap-termiusx2dapp-8.mount loaded active mounted Mount unit for termius-app

sys-fs-fuse-connections.mount loaded active mounted FUSE Control File System

sys-kernel-debug.mount loaded active mounted Debug File System

acpid.path loaded active running ACPI Events Check

cups.path loaded active running CUPS Scheduler

systemd-ask-password-plymouth.path loaded active waiting Forward Password Requests to Plymouth Directory Watch

systemd-ask-password-wall.path loaded active waiting Forward Password Requests to Wall Directory Watch

init.scope loaded active running System and Service Manager

session-c2.scope loaded active running Session c2 of user magi

accounts-daemon.service loaded active running Accounts Service

acpid.service loaded active running ACPI event daemon

anacron.service loaded active running Run anacron jobs

apache2.service loaded active running The Apache HTTP Server

apparmor.service loaded active exited AppArmor initialization

apport.service loaded active exited LSB: automatic crash report generation

aptik-battery-monitor.service loaded active running LSB: start/stop the aptik battery monitor daemon

atop.service loaded active running Atop advanced performance monitor

atopacct.service loaded active running Atop process accounting daemon

avahi-daemon.service loaded active running Avahi mDNS/DNS-SD Stack

colord.service loaded active running Manage, Install and Generate Color Profiles

console-setup.service loaded active exited Set console font and keymap

cron.service loaded active running Regular background program processing daemon

cups-browsed.service loaded active running Make remote CUPS printers available locally

cups.service loaded active running CUPS Scheduler

dbus.service loaded active running D-Bus System Message Bus

postfix.service loaded active exited Postfix Mail Transport Agent

UNIT 相應的 systemd 單元名稱

LOAD 相應的單元是否被加載到記憶體中

ACTIVE 該單元是否處于活動狀态

SUB 該單元是否處于運作狀态（LCTT 譯注：是較于 ACTIVE 更加詳細的狀态描述，不同的單元類型有不同的狀态。）

DESCRIPTION 關于該單元的簡短描述

以下選項可根據類型列出單元：

systemctl list-units --type service

fwupd.service loaded active running Firmware update daemon

[email protected] loaded active running Getty on tty1

grub-common.service loaded active exited LSB: Record successful boot for GRUB

irqbalance.service loaded active running LSB: daemon to balance interrupts for SMP systems

keyboard-setup.service loaded active exited Set the console keyboard layout

kmod-static-nodes.service loaded active exited Create list of required static device nodes for the current kernel

以下選項可幫助您根據狀态列出機關，輸出與前例類似但更直截了當：

systemctl list-unit-files --type service

UNIT FILE STATE

accounts-daemon.service enabled

acpid.service disabled

alsa-restore.service static

alsa-state.service static

alsa-utils.service masked

anacron-resume.service enabled

anacron.service enabled

apache-htcacheclean.service disabled

[email protected] disabled

apache2.service enabled

[email protected] disabled

apparmor.service enabled

[email protected] static

apport.service generated

apt-daily-upgrade.service static

apt-daily.service static

aptik-battery-monitor.service generated

atop.service enabled

atopacct.service enabled

[email protected] enabled

avahi-daemon.service enabled

bluetooth.service enabled

systemctl | grep apache2

或者，使用以下指令也可檢視指定服務的狀态：

systemctl status apache2

● apache2.service - The Apache HTTP Server

Loaded: loaded (/lib/systemd/system/apache2.service; enabled; vendor preset: enabled)

Drop-In: /lib/systemd/system/apache2.service.d

└─apache2-systemd.conf

Active: active (running) since Tue 2018-03-06 12:34:09 IST; 8min ago

Process: 2786 ExecReload=/usr/sbin/apachectl graceful (code=exited, status=0/SUCCESS)

Main PID: 1171 (apache2)

Tasks: 55 (limit: 4915)

CGroup: /system.slice/apache2.service

├─1171 /usr/sbin/apache2 -k start

├─2790 /usr/sbin/apache2 -k start

└─2791 /usr/sbin/apache2 -k start

Mar 06 12:34:08 magi-VirtualBox systemd[1]: Starting The Apache HTTP Server...

Mar 06 12:34:09 magi-VirtualBox apachectl[1089]: AH00558: apache2: Could not reliably determine the server's fully qualified domain name, using 10.0.2.15. Set the 'ServerName' directive globally to suppre

Mar 06 12:34:09 magi-VirtualBox systemd[1]: Started The Apache HTTP Server.

Mar 06 12:39:10 magi-VirtualBox systemd[1]: Reloading The Apache HTTP Server.

Mar 06 12:39:10 magi-VirtualBox apachectl[2786]: AH00558: apache2: Could not reliably determine the server's fully qualified domain name, using fe80::7929:4ed1:279f:4d65. Set the 'ServerName' directive gl

Mar 06 12:39:10 magi-VirtualBox systemd[1]: Reloaded The Apache HTTP Server.

執行以下指令，隻檢視正在運作的服務：

systemctl | grep running

lightdm.service loaded active running Light Display Manager

ModemManager.service loaded active running Modem Manager

NetworkManager.service loaded active running Network Manager

polkit.service loaded active running Authorization Manager

使用以下指令檢視系統啟動時會被啟用的服務清單：

systemctl list-unit-files | grep enabled

acpid.path enabled

cups.path enabled

console-setup.service enabled

cron.service enabled

cups-browsed.service enabled

cups.service enabled

display-manager.service enabled

dns-clean.service enabled

friendly-recovery.service enabled

[email protected] enabled

gpu-manager.service enabled

keyboard-setup.service enabled

lightdm.service enabled

ModemManager.service enabled

network-manager.service enabled

networking.service enabled

NetworkManager-dispatcher.service enabled

NetworkManager-wait-online.service enabled

NetworkManager.service enabled

systemd-cgtop 按資源使用情況（任務、CPU、記憶體、輸入和輸出）列出控制組：

systemd-cgtop

Control Group Tasks %CPU Memory Input/s Output/s

/ - - 1.5G - -

/init.scope 1 - - - -

/system.slice 153 - - - -

/system.slice/ModemManager.service 3 - - - -

/system.slice/NetworkManager.service 4 - - - -

/system.slice/accounts-daemon.service 3 - - - -

/system.slice/acpid.service 1 - - - -

/system.slice/apache2.service 55 - - - -

/system.slice/aptik-battery-monitor.service 1 - - - -

/system.slice/atop.service 1 - - - -

/system.slice/atopacct.service 1 - - - -

/system.slice/avahi-daemon.service 2 - - - -

/system.slice/colord.service 3 - - - -

/system.slice/cron.service 1 - - - -

/system.slice/cups-browsed.service 3 - - - -

/system.slice/cups.service 2 - - - -

/system.slice/dbus.service 6 - - - -

/system.slice/fwupd.service 5 - - - -

/system.slice/irqbalance.service 1 - - - -

/system.slice/lightdm.service 7 - - - -

/system.slice/polkit.service 3 - - - -

/system.slice/repowerd.service 14 - - - -

/system.slice/rsyslog.service 4 - - - -

/system.slice/rtkit-daemon.service 3 - - - -

/system.slice/snapd.service 8 - - - -

/system.slice/system-getty.slice 1 - - - -

同時，我們可以使用 pstree 指令（輸出來自 SysVinit 系統）檢視正在運作的服務：

pstree

init-+-crond

|-httpd---2*[httpd]

|-kthreadd/99149---khelper/99149

|-2*[mingetty]

|-mysqld_safe---mysqld---9*[{mysqld}]

|-rsyslogd---3*[{rsyslogd}]

|-saslauthd---saslauthd

|-2*[sendmail]

|-sshd---sshd---bash---pstree

|-udevd

`-xinetd

我們還可以使用 pstree 指令（輸出來自 systemd 系統）檢視正在運作的服務：

systemd─┬─ModemManager─┬─{gdbus}

│ └─{gmain}

├─NetworkManager─┬─dhclient

│ ├─{gdbus}

├─accounts-daemon─┬─{gdbus}

├─acpid

├─agetty

├─anacron

├─apache2───2[apache2───26[{apache2}]]

├─aptd───{gmain}

├─aptik-battery-m

├─atop

├─atopacctd

├─avahi-daemon───avahi-daemon

├─colord─┬─{gdbus}

├─cron

├─cups-browsed─┬─{gdbus}

├─cupsd

├─dbus-daemon

├─fwupd─┬─{GUsbEventThread}

│ ├─{fwupd}

├─gnome-keyring-d─┬─{gdbus}

│ ├─{gmain}

│ └─{timer}