第五章:系统服务

1.服务目录

 

在之前的Redhat Linux5.x&6.x的系统中,我们知道,系统的服务都是存放在/etc/init.d这个目录中的,但是在RHEL7.x的系统中,已经发生了改变,如下:

------------------------------------------查看RHEL7之前的系统服务路径------------------------------

[root@ freeit ~]# cd /etc/init.d/

[root@ freeit init.d]# ls

abrt-ccpp         iscsi           restorecond

abrtd             iscsid          rhnsd

abrt-oops         kdump           rhsmcertd

acpid             killall         rngd

atd               libvirt-guests  rpcbind

auditd            lldpad          rpcgssd

autofs            lvm2-lvmetad    rpcidmapd

blk-availability  lvm2-monitor    rpcsvcgssd

bluetooth         mdmonitor       rsyslog

certmonger        messagebus      sandbox

cgconfig          multipathd      saslauthd

cgred             mysqld          single

cpuspeed          named           smartd

crond             netconsole      snmpd

cups              netfs           snmptrapd

dhcpd             network         spice-vdagentd

dhcpd6            NetworkManager  sshd

dhcrelay          nfs             sssd

dnsmasq           nfslock         sysstat

fcoe              ntpd            udev-post

firstboot         ntpdate         vmware-tools

functions         oddjobd         vmware-tools-thinprint

haldaemon         openct          vncserver

halt              pcscd           wdaemon

htcacheclean      portreserve     winbind

httpd             postfix         wpa_supplicant

ip6tables         psacct          xinetd

iptables          quota_nld       ypbind

irqbalance        rdisc

-----------------------------------------查看RHEL7/etc/init.d/目录----------------------------------

[root@ freeit tmp]# cd /etc/init.d/

[root@ freeit init.d]# ls

functions   iprinit    netconsole  README

iprdump     iprupdate  network     rhnsd

//如上,此目录不再是系统服务的所在路径,所以,重启服务也不能使用/etc/init.d servername  restart来启动

 

 

 

2.服务下次启动状态

 

RHEL7.x之前的系统中,使用命令chkconfig –list即可查看所有服务的下次启动状态,但是在RHEL7中,此命令已不可用

[root@ freeit ~]# chkconfig --list

 

Note: This output shows SysV services  only and does not include native

       systemd services. SysV configuration data might be overridden by  native

       systemd configuration.

 

       If you want to list systemd services use 'systemctl list-unit-files'.

       To see services enabled on particular target use

       'systemctl list-dependencies [target]'.

 

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

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

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

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

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

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

//此命令列出的只是一些基本的服务。要想查看所有的,根据提示命令查看(加粗字体)

---------------------------------------------systemctl list-unit-files---------------------------------------------

[root@ freeit ~]# systemctl  list-unit-files

UNIT FILE                                   STATE  

proc-sys-fs-binfmt_misc.automount           static   

dev-hugepages.mount                         static 

dev-mqueue.mount                            static 

proc-fs-nfsd.mount                          static 

proc-sys-fs-binfmt_misc.mount               static 

sys-fs-fuse-connections.mount               static 

sys-kernel-config.mount                     static 

sys-kernel-debug.mount                      static 

tmp.mount                                   disabled

var-lib-nfs-rpc_pipefs.mount                static 

brandbot.path                               disabled

cups.path                                   enabled

systemd-ask-password-console.path           static 

systemd-ask-password-plymouth.path          static 

………………………..

 

 

 

3.系统运行级别

 

RHEL7中,系统的运行级别已没有0-6之说。运行级别的inittab文件也不再包含0-6级别的说明。如下:

[root@ freeit ~]# vim /etc/inittab

# inittab is no longer used when using  systemd.

#

# ADDING CONFIGURATION HERE WILL HAVE NO  EFFECT ON YOUR SYSTEM.

#

# Ctrl-Alt-Delete is handled by  /etc/systemd/system/ctrl-alt-del.targe

t

#

# systemd uses 'targets' instead of  runlevels. By default, there are t

wo main targets:

#

#  multi-user.target: analogous to runlevel 3

//相当于运行级别3,命令行界面

#  graphical.target: analogous to runlevel 5

//相当于运行级别5,图形化界面

#

# To set a default target, run:

#

# ln -sf /lib/systemd/system/<target  name>.target /etc/systemd/system/

default.target

#

~                                                                

 

查看系统缺省运行级别

[root@ freeit ~]# systemctl  get-default

graphical.target

//默认运行级别为图形化界面

 

设置默认运行级别

[root@ freeit ~]#systemctl set-default  multi-user.target

[root@ freeit ~]# systemctl get-default

multi-user.target

 

查看设置的运行级别的服务状态(下次启动状态)

[root@ freeit ~]# systemctl  list-unit-files |grep multi-user

multi-user.target                           enabled

 

 

 

 

4.服务下次启动状态

 

我们知道,服务启动之后,要想下次重启生效,RHEL7之前,要使用命令chkconfig servername on,但是在RHEL7中,已不能使用此命令。那么要如何设置,看下面的例子:

[root@ freeit ~]# systemctl restart  postfix.service

//启动邮件服务

[root@ freeit ~]# systemctl status  postfix.service

//查看邮件服务的运行状态

postfix.service - Postfix Mail Transport  Agent

    Loaded: loaded (/usr/lib/systemd/system/postfix.service; enabled)

//下次启动为开启

    Active: active (running) since Mon 2015-05-04 11:03:42 CST; 14s  ago

//当前正在运行

   Process: 4611 ExecStop=/usr/sbin/postfix stop (code=exited,  status=0/SUCCESS)

  Process: 4626 ExecStart=/usr/sbin/postfix  start (code=exited, status=0/SUCCESS)

   Process: 4623 ExecStartPre=/usr/libexec/postfix/chroot-update  (code=exited, status=0/SUCCESS)

   Process: 4621 ExecStartPre=/usr/libexec/postfix/aliasesdb  (code=exited, status=0/SUCCESS)

 Main PID: 4698 (master)

    CGroup: /system.slice/postfix.service

            ├─4698 /usr/libexec/postfix/master –w

            ├─4699 pickup -l -t unix -u

            └─4700 qmgr -l -t unix -u

 

May 04 11:03:42 localhost.localdomain  systemd[1]: Starting Postfix Ma...

May 04 11:03:42 localhost.localdomain  postfix/master[4698]: daemon st...

May 04 11:03:42 localhost.localdomain  systemd[1]: Started Postfix Mai...

Hint: Some lines were ellipsized, use -l  to show in full.

 

------------------------------------------------关闭下次开机启动-------------------------------------------

[root@ freeit ~]# systemctl disable  postfix.service

rm  '/etc/systemd/system/multi-user.target.wants/postfix.service'

[root@ freeit ~]# systemctl status  postfix.service 

postfix.service - Postfix Mail Transport  Agent

    Loaded: loaded (/usr/lib/systemd/system/postfix.service; disabled)

    Active: active (running) since Mon  2015-05-04 11:03:42 CST; 4min 30s ago

 Main PID: 4698 (master)

    CGroup: /system.slice/postfix.service

            ├─4698 /usr/libexec/postfix/master -w

            ├─4699 pickup -l -t unix -u

            └─4700 qmgr -l -t unix -u

 

May 04 11:03:42 localhost.localdomain  systemd[1]: Starting Postfix Ma...

May 04 11:03:42 localhost.localdomain  postfix/master[4698]: daemon st...

May 04 11:03:42 localhost.localdomain  systemd[1]: Started Postfix Mai...

Hint: Some lines were ellipsized, use -l  to show in full.

//下次重启生效功能关闭之后,重启系统,邮件服务即为关闭状态

 

关闭之后重启验证

[root@ freeit ~]# systemctl status  postfix.service

postfix.service - Postfix Mail Transport  Agent

    Loaded: loaded (/usr/lib/systemd/system/postfix.service; disabled)

    Active: inactive (dead)

//没有启动

 

 

重新启动邮件服务,并设置下次开机启动

 [root@ freeit ~]# systemctl restart postfix

[root@localhost ~]# systemctl enable  postfix.service

ln -s '/usr/lib/systemd/system/postfix.service'  '/etc/systemd/system/multi-user.target.wants/postfix.service'

[root@ freeit ~]# systemctl status  postfix.service

postfix.service - Postfix Mail Transport  Agent

    Loaded: loaded (/usr/lib/systemd/system/postfix.service; enabled)

    Active: active (running) since Mon 2015-05-04 11:12:14 CST; 35s  ago

 Main PID: 2994 (master)

    CGroup: /system.slice/postfix.service

            ├─2994 /usr/libexec/postfix/master -w

            ├─2995 pickup -l -t unix -u

            └─2996 qmgr -l -t unix -u

 

May 04 11:12:14 localhost.localdomain  systemd[1]: Starting Postfix Ma...

May 04 11:12:14 localhost.localdomain  postfix/master[2994]: daemon st...

May 04 11:12:14 localhost.localdomain  systemd[1]: Started Postfix Mai...

Hint: Some lines were ellipsized, use -l  to show in full.

 

 

 

5.服务状态相关命令

 

  • 查看当前启动状态

[root@ freeit ~]# systemctl is-active  postfix.service

Active

//当前正在运行

 

  • 关闭当前运行状态,再次查看

[root@ freeit ~]# systemctl stop  postfix.service

[root@ freeit ~]# systemctl is-active  postfix.service

inactive

 

  • 查看下次开机启动状态

[root@ freeit ~]# systemctl is-enabled  postfix.service

enabled

//下次开机为启动

 

  • 关闭下次开机启动,并再次查看

[root@ freeit ~]# systemctl disable  postfix.service

rm '/etc/systemd/system/multi-user.target.wants/postfix.service'

[root@localhost ~]# systemctl is-enabled  postfix.service

disabled

 

 

 

6.锁定服务(mask)

 

1:对postfix服务执行mask操作,然后执行重启操作

[root@ freeit ~]# systemctl mask postfix

ln -s '/dev/null' '/etc/systemd/system/postfix.service'

[root@localhost ~]# systemctl restart  postfix

Failed to issue method call: Unit  postfix.service is masked.

//重启服务失败

[root@ freeit ~]# systemctl status  postfix

postfix.service

    Loaded: masked (/dev/null)

    Active: inactive (dead)

 

May 04 11:12:14 localhost.localdomain  systemd[1]: Starting Postfix Ma...

May 04 11:12:14 localhost.localdomain  postfix/master[2994]: daemon st...

May 04 11:12:14 localhost.localdomain  systemd[1]: Started Postfix Mai...

May 04 11:18:39 localhost.localdomain  systemd[1]: Stopping Postfix Ma...

May 04 11:18:39 localhost.localdomain  systemd[1]: Stopped Postfix Mai...

Hint: Some lines were ellipsized, use -l  to show in full.

 

2:解锁服务并再次重启

[root@ freeit ~]# systemctl unmask  postfix

//解锁

rm '/etc/systemd/system/postfix.service'

[root@ freeit ~]# systemctl restart  postfix

//重启成功

[root@ freeit ~]# systemctl status  postfix 

postfix.service - Postfix Mail Transport  Agent

    Loaded: loaded (/usr/lib/systemd/system/postfix.service; disabled)

    Active: active (running) since Mon 2015-05-04 11:29:36 CST; 3s  ago

   Process: 3529 ExecStart=/usr/sbin/postfix start (code=exited,  status=0/SUCCESS)

   Process: 3527 ExecStartPre=/usr/libexec/postfix/chroot-update  (code=exited, status=0/SUCCESS)

   Process: 3524 ExecStartPre=/usr/libexec/postfix/aliasesdb  (code=exited, status=0/SUCCESS)

 Main PID: 3601 (master)

    CGroup: /system.slice/postfix.service

            ├─3601 /usr/libexec/postfix/master -w

            ├─3602 pickup -l -t unix -u

            └─3603 qmgr -l -t unix -u

 

May 04 11:29:36 localhost.localdomain  postfix/master[3601]: daemon st...

May 04 11:29:36 localhost.localdomain  systemd[1]: Started Postfix Mai...

Hint: Some lines were ellipsized, use -l  to show in full.

 

 

7.系统进程

 

 

7.1.实时查看系统进程

 

top  - 11:34:23 up 25 min,  1 user,  load average: 0.00, 0.01, 0.05

Tasks:  297 total,   4 running, 293  sleeping,   0 stopped,   0 zombie

%Cpu(s):  0.0 us,   0.0 sy,  0.0 ni, 99.7 id,  0.0 wa,   0.0 hi,  0.3 si,  0.0 st

KiB  Mem:   1010788 total,   306908 used,   703880 free,     1080 buffers

KiB  Swap:  2097148 total,        0 used,  2097148 free.   110788 cached Mem

 

  PID USER      PR   NI    VIRT    RES     SHR S %CPU %MEM     TIME+  COMMAND                  

 3651 root      20    0  123788   1772    1148 R  0.3  0.2    0:00.03 top                        

     1 root      20   0    53948   7808   2548 S   0.0  0.8   0:05.08 systemd                  

     2 root      20   0        0      0      0 S   0.0  0.0   0:00.00 kthreadd                 

     3 root      20   0        0      0       0 R  0.0  0.0    0:00.04 ksoftirqd/0                

     5 root       0 -20       0       0      0 S  0.0   0.0   0:00.00 kworker/0:0H             

     7 root      rt   0        0      0      0 S   0.0  0.0   0:00.00 migration/0              

8 root      20    0       0      0       0 S  0.0  0.0    0:00.00 rcu_bh     

…………………..

--------------------------------------------更详细查看,按1-------------------------------------------------

 top - 11:35:00 up 25 min,  1 user,   load average: 0.00, 0.01, 0.05

Tasks: 297 total,   2 running, 295 sleeping,   0 stopped,   0 zombie

%Cpu0  :   0.7 us,  0.7 sy,  0.0 ni, 98.7 id,  0.0 wa,   0.0 hi,  0.0 si,  0.0 st

KiB Mem:    1010788 total,   307172  used,   703616 free,     1080 buffers

KiB Swap:   2097148 total,        0  used,  2097148 free.   110788 cached Mem

 

   PID USER      PR  NI     VIRT    RES    SHR S %CPU %MEM     TIME+ COMMAND                  

   879 root      20   0   193424   4168   3344 S   1.0  0.4   0:02.80 vmtoolsd                 

 3651 root      20    0  123788   1772    1148 R  0.7  0.2    0:00.20 top                        

     1 root      20   0    53948   7808   2548 S   0.0  0.8   0:05.08 systemd                  

     2 root      20   0        0      0      0 S   0.0  0.0   0:00.00 kthreadd                 

     3 root      20   0        0      0      0 S   0.0  0.0   0:00.04 ksoftirqd/0              

     5 root       0 -20       0       0      0 S  0.0   0.0   0:00.00 kworker/0:0H             

     7 root      rt   0        0      0      0  S  0.0   0.0   0:00.00 migration/0              

     8 root      20   0        0      0      0 S   0.0  0.0   0:00.00 rcu_bh      

q键退出进程

 

  • 5行说明:

5行是系统整体的统计信息

  • 第一行是任务队列信息,同uptime(查看服务器启动时间)命令的执行结果。内容如下:

  • 11:34:23:当前时间;

  • up  1:13:系统运行时间,格式为时:分;

  • 1 user:当前登录用户数;

  • load average: 0.00, 0.01, 0.05:系统负载,即任务队列的平均长度。三个数值分别为1分钟、5分钟、15分钟前到现在的平均值。

  • 第二、三行为进程和CPU的信息。当有多个CPU时,这些内容可能会超过两行,内容如下:

  • Tasks: 297 total:进程总数;

  • 4 running:正在运行的进程数;

  • 293 sleeping:睡眠的进程数;

  • 0 stopped:停止进程数;

  • 0 zombie:僵尸进程;

  • %Cpu(s):  0.0 us:用户空间占用CPU百分比;

  • 0.0 sy:内核空间占用CPU百分比; 

  • 0.0 ni:用户进程空间内改变过优先级的进程占用CPU百分比;

  • 99.7 idid空闲CPU百分比; 

  • 0.0 wawa等待输入输出的CPU时间百分比 

  • 0.0 hi  0.3 si, 0.0 st

  • 最后两行为内存信息。内容如下:

  • KiB Mem:   1010788 total:物理内存总量

  • 306908 used:使用的物理内存总量;

  • 703880 free:空闲的物理内存总量;

  • 1080 buffers:用作内核缓存的物理内存量;

  • KiB Swap:  2097148 total:交换区总量;

  • 0 used:使用的交换分区总量;

  • 2097148 free:空闲的交换区总量;

  • 110788 cached Mem:缓冲的交换区总量。

 

  • 进程区信息说明:

  • PID:进程ID

  • USER:进程所有者;

  • PR:进程优先级;

  • NInice值。负值表示高优先级;正值表示低优先级;

  • VIRT:进程使用的虚拟内存总量,单位KbVITR=SWAP+RES

  • RES:进程使用的、未被交换出的物理内存大小,单位KBRES=CODE+DATA

  • SHR:共享内存大小,单位Kb

  • S:进程状态;

  • %CPU:上次更新到现在的CPU时间战用百分比;

  • %MEM:进程使用的物理内存百分比;

  • TIME+:进程使用的CPU时间总计,单位1/100秒;

  • COMMAND:命令名/命令行

 

 

7.2.静态查看当前进程状态

 

[root@ freeit ~]# ps aux

USER        PID %CPU %MEM    VSZ   RSS TTY      STAT START   TIME COMMAND

root         1   0.3  0.7  53948   7808 ?        Ss   11:09    0:05 /usr/lib/systemd/systemd --s

root         2   0.0  0.0      0      0 ?        S    11:09    0:00 [kthreadd]

root         3   0.0  0.0      0      0 ?        S    11:09    0:00 [ksoftirqd/0]

root         5   0.0  0.0      0      0 ?        S<   11:09    0:00 [kworker/0:0H]

root         7   0.0  0.0      0      0 ?        S    11:09    0:00 [migration/0]

root         8   0.0  0.0      0      0 ?        S    11:09    0:00 [rcu_bh]

root         9   0.0  0.0      0      0 ?        S    11:09    0:00 [rcuob/0]

root        10   0.0  0.0      0      0 ?        S    11:09    0:00 [rcuob/1]

root        11   0.0  0.0      0      0 ?        S    11:09    0:00 [rcuob/2]

root        12   0.0  0.0      0      0 ?        S    11:09    0:00 [rcuob/3]

………………………….

常用参数:

     -a:包含所有终端的进程

     -u:显示进程的拥有者

     -x:显示不属于任何终端的进程

     -f:显示进程的父子关系

 

 

7.3.查看进程树

 

[root@ freeit ~]# pstree

systemd─┬─ModemManager───2*[{ModemManager}]

         ├─NetworkManager───2*[{NetworkManager}]

         ├─2*[abrt-watch-log]

         ├─abrtd

         ├─agetty

         ├─alsactl

         ├─atd

         ├─auditd─┬─audispd─┬─sedispatch

                          └─{audispd}

                 └─{auditd}

         ├─avahi-daemon───avahi-daemon

         ├─bluetoothd

         ├─chronyd

         ├─crond

         ├─dbus-daemon───{dbus-daemon}

         ├─firewalld───{firewalld}

         ├─iprdump

         ├─iprinit

         ├─iprupdate

         ├─ksmtuned───sleep

         ├─libvirtd───10*[{libvirtd}]

         ├─lsmd

         ├─lvmetad

         ├─master─┬─pickup

                 └─qmgr

         ├─packagekitd───2*[{packagekitd}]

         ├─polkitd───5*[{polkitd}]

         ├─rhsmcertd

         ├─rngd

         ├─rpc.statd

         ├─rpcbind

         ├─rsyslogd───2*[{rsyslogd}]

         ├─smartd

         ├─sshd───sshd───bash───pstree

         ├─systemd-journal

         ├─systemd-logind

         ├─systemd-udevd

         ├─tuned───4*[{tuned}]

         └─vmtoolsd

 

 

 

8.前台后台(fg&bg)

 

例:把/usr复制到/tmp下,由于复制时间长,调用到后台复制。然后再调用到前台。期间再暂停,调用到后台,最后kill掉此进程

[root@ freeit ~]# cp -r /usr /tmp/ &

[1] 3991

//开始复制,&为后台执行

 

[root@ freeit ~]# jobs

[1]+   Running                 cp -i -r  /usr /tmp/ &

//查看后台执行的操作

 

[root@ freeit ~]# fg 1

cp -i -r /usr /tmp/

//调用到前台执行进程

^Z

[1]+   Stopped                 cp -i -r  /usr /tmp

//ctrl+z停止进程

 

[root@ freeit ~]# bg 1

[1]+ cp -i -r /usr /tmp/ &

//继续调用到后台执行

 

[root@ freeit ~]# jobs

[1]+   Running                 cp -i -r  /usr /tmp/ &

 

 [root@ freeit ~]# kill %1

//结束此进程

 

[root@ freeit ~]# jobs

[1]+   Terminated              cp -i -r  /usr /tmp/