第五章：系統服務
1.服務目錄
在之前的Redhat Linux5.x&6.x的系統中，我們知道，系統的服務都是存放在/etc/init.d這個目錄中的，但是在RHEL7.x的系統中，已經發生了改變，如下：
------------------------------------------查看RHEL7之前的系統服務路徑------------------------------ [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的/etc/init.d/目錄---------------------------------- [root@ freeit tmp]# cd /etc/init.d/ [root@ freeit init.d]# ls functions iprinit netconsole README iprdump iprupdate network rhnsd //如上，此目錄不再是系統服務的所在路徑，所以，重啓服務也不能使用/etc/init.d servername restart來啓動 |
2.服務下次啓動狀態
在RHEL7.x之前的系統中，使用命令chkconfig –list即可查看所有服務的下次啓動狀態，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務。要想查看所有的，根據提示命令查看(加粗字體) ---------------------------------------------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.系統運行級別
RHEL7中，系統的運行級別已沒有0-6之說。運行級別的inittab文件也不再包含0-6級別的說明。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 //相當於運行級別3，命令行界面 # graphical.target: analogous to runlevel 5 //相當於運行級別5，圖形化界面 # # To set a default target, run: # # ln -sf /lib/systemd/system/<target name>.target /etc/systemd/system/ default.target # ~ |
查看系統缺省運行級別
[root@ freeit ~]# systemctl get-default graphical.target //默認運行級別爲圖形化界面 |
設置默認運行級別
[root@ freeit ~]#systemctl set-default multi-user.target [root@ freeit ~]# systemctl get-default multi-user.target |
查看設置的運行級別的服務狀態(下次啓動狀態)
[root@ freeit ~]# systemctl list-unit-files |grep multi-user multi-user.target enabled
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4.服務下次啓動狀態
我們知道，服務啓動之後，要想下次重啓生效，RHEL7之前，要使用命令chkconfig servername on，但是在RHEL7中，已不能使用此命令。那麼要如何設置，看下面的例子：
[root@ freeit ~]# systemctl restart postfix.service //啓動郵件服務 [root@ freeit ~]# systemctl status postfix.service //查看郵件服務的運行狀態 postfix.service - Postfix Mail Transport Agent Loaded: loaded (/usr/lib/systemd/system/postfix.service; enabled) //下次啓動爲開啓 Active: active (running) since Mon 2015-05-04 11:03:42 CST; 14s ago //當前正在運行 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.
------------------------------------------------關閉下次開機啓動------------------------------------------- [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. //下次重啓生效功能關閉之後，重啓系統，郵件服務即爲關閉狀態 |
關閉之後重啓驗證
[root@ freeit ~]# systemctl status postfix.service postfix.service - Postfix Mail Transport Agent Loaded: loaded (/usr/lib/systemd/system/postfix.service; disabled) Active: inactive (dead) //沒有啓動
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重新啓動郵件服務，並設置下次開機啓動
[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.服務狀態相關命令
查看當前啓動狀態
[root@ freeit ~]# systemctl is-active postfix.service Active //當前正在運行 |
關閉當前運行狀態，再次查看
[root@ freeit ~]# systemctl stop postfix.service [root@ freeit ~]# systemctl is-active postfix.service inactive |
查看下次開機啓動狀態
[root@ freeit ~]# systemctl is-enabled postfix.service enabled //下次開機爲啓動 |
關閉下次開機啓動，並再次查看
[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.鎖定服務(mask)
例1：對postfix服務執行mask操作，然後執行重啓操作
[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. //重啓服務失敗 [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. |
例2：解鎖服務並再次重啓
[root@ freeit ~]# systemctl unmask postfix //解鎖 rm '/etc/systemd/system/postfix.service' [root@ freeit ~]# systemctl restart postfix //重啓成功 [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.系統進程
7.1.實時查看系統進程
按q鍵退出進程
前5行說明：
前5行是系統整體的統計信息
第一行是任務隊列信息，同uptime(查看服務器啓動時間)命令的執行結果。內容如下：
11:34:23：當前時間；
up 1:13：系統運行時間，格式爲時：分；
1 user：當前登錄用戶數；
load average: 0.00, 0.01, 0.05：系統負載，即任務隊列的平均長度。三個數值分別爲1分鐘、5分鐘、15分鐘前到現在的平均值。
第二、三行爲進程和CPU的信息。當有多個CPU時，這些內容可能會超過兩行，內容如下：
Tasks: 297 total：進程總數；
4 running：正在運行的進程數；
293 sleeping：睡眠的進程數；
0 stopped:停止進程數；
0 zombie：殭屍進程；
%Cpu(s): 0.0 us：用戶空間佔用CPU百分比；
0.0 sy：內核空間佔用CPU百分比；
0.0 ni：用戶進程空間內改變過優先級的進程佔用CPU百分比；
99.7 id：id空閒CPU百分比；
0.0 wa：wa等待輸入輸出的CPU時間百分比
0.0 hi 0.3 si, 0.0 st
最後兩行爲內存信息。內容如下：
KiB Mem: 1010788 total：物理內存總量
306908 used：使用的物理內存總量；
703880 free：空閒的物理內存總量；
1080 buffers：用作內核緩存的物理內存量；
KiB Swap: 2097148 total：交換區總量；
0 used：使用的交換分區總量；
2097148 free：空閒的交換區總量；
110788 cached Mem：緩衝的交換區總量。
進程區信息說明：
PID：進程ID；
USER：進程所有者；
PR：進程優先級；
NI：nice值。負值表示高優先級；正值表示低優先級；
VIRT：進程使用的虛擬內存總量，單位Kb，VITR=SWAP+RES
RES：進程使用的、未被交換出的物理內存大小，單位KB，RES=CODE+DATA
SHR：共享內存大小，單位Kb；
S：進程狀態；
%CPU：上次更新到現在的CPU時間戰用百分比；
%MEM：進程使用的物理內存百分比；
TIME+：進程使用的CPU時間總計，單位1/100秒；
COMMAND:命令名/命令行
7.2.靜態查看當前進程狀態
[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] …………………………. |
常用參數：
-a：包含所有終端的進程
-u：顯示進程的擁有者
-x：顯示不屬於任何終端的進程
-f：顯示進程的父子關係
7.3.查看進程樹
[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.前臺後臺(fg&bg)
例：把/usr複製到/tmp下，由於複製時間長，調用到後臺複製。然後再調用到前臺。期間再暫停，調用到後臺，最後kill掉此進程
[root@ freeit ~]# cp -r /usr /tmp/ & [1] 3991 //開始複製，&爲後臺執行
[root@ freeit ~]# jobs [1]+ Running cp -i -r /usr /tmp/ & //查看後臺執行的操作
[root@ freeit ~]# fg 1 cp -i -r /usr /tmp/ //調用到前臺執行進程 ^Z [1]+ Stopped cp -i -r /usr /tmp //按ctrl+z停止進程
[root@ freeit ~]# bg 1 [1]+ cp -i -r /usr /tmp/ & //繼續調用到後臺執行
[root@ freeit ~]# jobs [1]+ Running cp -i -r /usr /tmp/ &
[root@ freeit ~]# kill %1 //結束此進程
[root@ freeit ~]# jobs [1]+ Terminated cp -i -r /usr /tmp/ |