08.18 如何查看 Linux 中所有正在運行的服務

有許多方法和工具可以查看 Linux 中所有正在運行的服務。大多數管理員會在 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。

以上命令可以清楚地顯示該服務是否在服務器上運行，這也是每個 Linux 管理員都該知道的非常簡單和基礎的命令。

如果你對系統環境並不熟悉，也不清楚系統在運行哪些服務，你會如何檢查？

是的，我們的確有必要這樣檢查一下。這將有助於我們瞭解系統上運行了什麼服務，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行的第一個進程。init 是一個守護進程，它將持續運行直至關機。

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 是一個基於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 發行版所採用

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。由於 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適用於 systemd 系統。

什麼是 Upstart 初始化系統

Upstart 是一個基於事件的 /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，並在系統運行時監控它們。

它最初是為 Ubuntu 發行版開發的，但其是以適合所有 Linux 發行版的開發為目標的，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適應的新的標準初始化系統。systemctl 是一個 systemd 管理工具，它可以幫助我們管理 systemd 系統。

方法一：如何在 System V（SysV）系統中查看運行的服務

以下命令可以幫助我們列出 System V（SysV） 系統中所有正在運行的服務。

如果服務很多，我建議使用文件查看命令，如 less、more 等，以便得到清晰的結果。

# service --status-all
或
# service --status-all | more
或
# 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
13 REJECT all ::/0 ::/0 reject-with icmp6-adm-prohibited
Chain FORWARD (policy ACCEPT)
num target prot opt source destination
1 REJECT all ::/0 ::/0 reject-with icmp6-adm-prohibited
Chain OUTPUT (policy ACCEPT)
num target prot opt source destination
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...

執行以下命令，可以只查看正在運行的服務：

# service --status-all | grep running
crond (pid 535) is running...
httpd (pid 627) is running...
mysqld (pid 911) is running...
rndc: neither /etc/rndc.conf nor /etc/rndc.key was found
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...

運行以下命令以查看指定服務的狀態：

# service --status-all | grep httpd
httpd (pid 627) is running...

或者，使用以下命令也可以查看指定服務的狀態：

# service httpd status
httpd (pid 627) is running... 

使用以下命令查看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
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）系統中查看運行的服務

另外一種在 Linux 系統上列出運行的服務的方法是使用 initctl 命令：

# 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 系統中查看運行的服務

以下命令幫助我們列出 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-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 
 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內存中

◈ ACTIVE 該單元是否處於活動狀態

◈ SUB 該單元是否處於運行狀態（LCTT 譯註：是較於 ACTIVE 更加詳細的狀態描述，不同的單元類型有不同的狀態。）

◈ DESCRIPTION 關於該單元的簡短描述

以下選項可根據類型列出單元：

# systemctl list-units --type service
 UNIT LOAD ACTIVE SUB DESCRIPTION 
 accounts-daemon.service loaded active running Accounts Service 
 acpid.service loaded active running ACPI event daemon 
 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態列出單位，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 
 

運行以下命令以查看指定服務的狀態：

# systemctl | grep apache2
 apache2.service loaded active running The Apache HTTP Server

或者，使用以下命令也可查看指定服務的狀態：

# 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.

執行以下命令，只查看正在運行的服務：

# systemctl | grep running
 acpid.path loaded active running ACPI Events Check 
 cups.path loaded active running CUPS Scheduler 
 init.scope loaded active running System and Service Manager 
 session-c2.scope loaded active running Session c2 of user magi 
 polkit.service loaded active running Authorization Manager 

使用以下命令查看系統啟動時會被啟用的服務列表：

# systemctl list-unit-files | grep enabled 

acpid.path enabled 
cups.path enabled 
accounts-daemon.service enabled 
anacron-resume.service enabled 
anacron.service enabled 
apache2.service enabled 
apparmor.service enabled 
atop.service enabled 
atopacct.service enabled 
[email protected] enabled 
avahi-daemon.service enabled 
bluetooth.service 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、內存、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/system-getty.slice 1 - - - -

同時，我們可以使用 pstree 命令（輸出來自 SysVinit 系統）查看正在運行的服務：

# 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 命令（輸出來自 systemd 系統）查看正在運行的服務：

# pstree
systemd─┬─ModemManager─┬─{gdbus}
 │ └─{gmain}
 ├─NetworkManager─┬─dhclient
 │ ├─{gdbus}
 │ └─{gmain}
 ├─accounts-daemon─┬─{gdbus}
 │ └─{gmain}
 ├─acpid
 ├─agetty
 ├─anacron
 ├─apache2───2*[apache2───26*[{apache2}]]
 ├─aptd───{gmain}
 ├─aptik-battery-m
 ├─atop
 ├─atopacctd
 ├─avahi-daemon───avahi-daemon
 ├─colord─┬─{gdbus}
 │ └─{gmain}
 ├─cron
 ├─cups-browsed─┬─{gdbus}
 │ └─{gmain}
 ├─cupsd
 ├─dbus-daemon
 ├─fwupd─┬─{GUsbEventThread}
 │ ├─{fwupd}
 │ ├─{gdbus} 

 │ └─{gmain}
 ├─gnome-keyring-d─┬─{gdbus}
 │ ├─{gmain}
 │ └─{timer}

方法四：如何使用 chkservice 在 systemd 系統中查看正在運行的服務

chkservice 是一個管理系統單元的終端工具，需要超級用戶權限。

# chkservice

要查看幫助頁面，請按下 ? ，它將顯示管理 systemd 服務的可用選項。

注：文章引自Linux中國微信公眾號