查看服务进程：ps aux

查看服务cpu利用：top

查看服务对应端口：netstat -nlp

以上命令可以清楚地显示该服务是否在服务器上运行，这也是每个 Linux 管理员都该知道的非常简单和基础的命令。

如果你对系统环境并不熟悉，也不清楚系统在运行哪些服务，你会如何检查？

是的，我们的确有必要这样检查一下。这将有助于我们了解系统上运行了什么服务，以及哪些是必要的、哪些需要被禁用。

init（初始化initialization的简称）是在系统启动期间运行的第一个进程。init 是一个守护进程，它将持续运行直至关机。

大多数 Linux 发行版都使用如下的初始化系统之一：

System V 是更老的初始化系统

Upstart 是一个基于事件的传统的初始化系统的替代品

systemd 是新的初始化系统，它已经被大多数最新的 Linux 发行版所采用

什么是 System V（SysV）

SysV（意即 System V） 初始化系统是早期传统的初始化系统和系统管理器。由于 sysVinit 系统上一些长期悬而未决的问题，大多数最新的发行版都适用于 systemd 系统。

什么是 Upstart 初始化系统

Upstart 是一个基于事件的 /sbin/init 的替代品，它控制在启动时的任务和服务的开始，在关机时停止它们，并在系统运行时监控它们。

它最初是为 Ubuntu 发行版开发的，但其是以适合所有 Linux 发行版的开发为目标的，以替换过时的 System-V 初始化系统。

什么是 systemd

systemd 是一个新的初始化系统以及系统管理器，它已成为大多数 Linux 发行版中非常流行且广泛适应的新的标准初始化系统。systemctl 是一个 systemd 管理工具，它可以帮助我们管理 systemd 系统。

方法一：如何在 System V（SysV）系统中查看运行的服务

以下命令可以帮助我们列出 System V（SysV） 系统中所有正在运行的服务。

如果服务很多，我建议使用文件查看命令，如 less、more 等，以便得到清晰的结果。

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

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)

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…

执行以下命令，可以只查看正在运行的服务：

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…

运行以下命令以查看指定服务的状态：

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务的状态：

service httpd status

httpd (pid 627) is running…

使用以下命令查看系统启动时哪些服务会被启用：

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）系统中查看运行的服务

另外一种在 Linux 系统上列出运行的服务的方法是使用 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 系统中查看运行的服务

以下命令帮助我们列出 systemd 系统中所有服务：

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 相应的 systemd 单元名称

LOAD 相应的单元是否被加载到内存中

ACTIVE 该单元是否处于活动状态

SUB 该单元是否处于运行状态（LCTT 译注：是较于 ACTIVE 更加详细的状态描述，不同的单元类型有不同的状态。）

DESCRIPTION 关于该单元的简短描述

以下选项可根据类型列出单元：

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

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

fwupd.service loaded active running Firmware update daemon

getty@tty1.service 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

以下选项可帮助您根据状态列出单位，输出与前例类似但更直截了当：

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

apache-htcacheclean@.service disabled

apache2.service enabled

apache2@.service disabled

apparmor.service enabled

apport-forward@.service static

apport.service generated

apt-daily-upgrade.service static

apt-daily.service static

aptik-battery-monitor.service generated

atop.service enabled

atopacct.service enabled

autovt@.service enabled

avahi-daemon.service enabled

bluetooth.service enabled

运行以下命令以查看指定服务的状态：

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务的状态：

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.

执行以下命令，只查看正在运行的服务：

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

accounts-daemon.service loaded active running Accounts Service

acpid.service loaded active running ACPI event daemon

apache2.service loaded active running The Apache HTTP Server

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

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

fwupd.service loaded active running Firmware update daemon

getty@tty1.service loaded active running Getty on tty1

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

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

使用以下命令查看系统启动时会被启用的服务列表：

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

autovt@.service 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

getty@.service 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 按资源使用情况（任务、CPU、内存、输入和输出）列出控制组：

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 – – – –

同时，我们可以使用 pstree 命令（输出来自 SysVinit 系统）查看正在运行的服务：

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

我们还可以使用 pstree 命令（输出来自 systemd 系统）查看正在运行的服务：

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}