Shulou(Shulou.com)06/03 Report--

Chapter 5: system Services

1. Service catalog

In the previous Redhat Linux5.x&6.x system, we know that the services of the system are stored in the / etc/init.d directory, but in the RHEL7.x system, it has changed as follows:

-- View the system service path before RHEL7--

[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

-- check the / etc/init.d/ directory of RHEL7--

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

[root@ freeit init.d] # ls

Functions iprinit netconsole README

Iprdump iprupdate network rhnsd

/ / as above, this directory is no longer the path where the system service is located, so the restart service cannot be started using / etc/init.d servername restart

two。 Next startup status of the service

On systems before RHEL7.x, the command chkconfig-list can be used to view the next startup status of all services, but in RHEL7, this command is no longer available

[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

/ / this command lists only some basic services. To see all of them, follow the prompt (bold font)

-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. System operation level

In RHEL7, the running level of the system is no longer 0-6. Run-level inittab files no longer contain 0-6 level descriptions. As follows:

[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

/ / equivalent to runlevel 3, command line interface

# graphical.target: analogous to runlevel 5

/ / equivalent to runlevel 5, graphical interface

#

# To set a default target, run:

#

# ln-sf / lib/systemd/system/.target / etc/systemd/system/

Default.target

#

~

View the system default run level

[root@ freeit ~] # systemctl get-default

Graphical.target

/ / the default run level is graphical interface

Set the default run level

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

[root@ freeit ~] # systemctl get-default

Multi-user.target

View the service status of the set runlevel (next startup status)

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

Multi-user.target enabled

4. Next startup status of the service

We know that for the next restart to take effect after the service is started, the command chkconfig servername on is used before RHEL7, but it is no longer available in RHEL7. So how to set it up, look at the following example:

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

/ / start the mail service

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

/ / View the running status of the mail service

Postfix.service-Postfix Mail Transport Agent

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

/ / enable the next startup

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

/ / currently running

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.

-turn it off and start it up next time-

[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.

/ / after the next restart takes effect, restart the system and the mail service will be turned off.

Restart verification after shutdown

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

Postfix.service-Postfix Mail Transport Agent

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

Active: inactive (dead)

/ / not started

Restart the mail service and set the next boot

[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. Service status related commands

View current startup status

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

Active

/ / currently running

Close the current running status and view it again

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

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

Inactive

Check the next boot status

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

Enabled

/ / the next boot will start.

Turn off the next boot and check it again

[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. Locking Service (mask)

Example 1: perform a mask operation on the postfix service, and then perform a restart operation

[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.

/ / failed to restart the service

[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.

Example 2: unlock the service and restart again

[root@ freeit ~] # systemctl unmask postfix

/ / unlock

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

[root@ freeit ~] # systemctl restart postfix

/ / restart successfully

[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. System process 7.1. View the system process in real time

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 00 00 S 0.0 0.00: 00.00 kthreadd

3 root 20 00 00 R 0.0 0.0 0:00.04 ksoftirqd/0

5 root 0-20 000 S 0.0 0.00: 00.00 kworker/0:0H

7 root rt 00 00 S 0.0 0.00: 00.00 migration/0

8 root 20 00 00 S 0.0 0.00: 00.00 rcu_bh

... ..

-for a more detailed view, press 1muri-

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 0.20: 00.20 top

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

2 root 20 00 00 S 0.0 0.00: 00.00 kthreadd

3 root 20 00 00 S 0.0 0.0 0:00.04 ksoftirqd/0

5 root 0-20 000 S 0.0 0.00: 00.00 kworker/0:0H

7 root rt 00 00 S 0.0 0.00: 00.00 migration/0

8 root 20 00 00 S 0.0 0.00: 00.00 rcu_bh

Press Q key to exit the process

The first 5 lines say:

The first five lines are statistics of the system as a whole.

The first line is the task queue information, which is the same as the execution result of the uptime (View server startup time) command. The contents are as follows:

11:34:23: current time

Up 1:13: system run time, format: hours: minutes

1 user: number of currently logged in users

Load average: 0.00,0.01,0.05: system load, that is, the average length of the task queue. The three values are the average values from 1 minute, 5 minutes and 15 minutes ago to the present.

Second, third behavior process and CPU information. When there is more than one CPU, the content may be more than two lines, as follows:

Tasks: 297 total: total number of processes

4 running: number of processes running

293 sleeping: number of sleep processes

0 stopped: number of stopped processes

0 zombie: zombie process

% Cpu (s): 0.0 us: percentage of CPU occupied by user space

0.0 sy: percentage of CPU occupied by kernel space

0.0 ni: percentage of CPU occupied by processes that have changed priorities in the user's process space

99.7% id:id idle CPU

0.0 percentage of CPU time wa:wa waits for input and output

0.0 hi 0.3 si, 0.0 st

The last two behaviors are memory information. The contents are as follows:

KiB Mem: 1010788 total: total physical memory

306908 used: total amount of physical memory used

703880 free: total amount of physical memory free

1080 buffers: amount of physical memory used as kernel cache

KiB Swap: 2097148 total: total exchange area

0 used: the total number of swap partitions used

2097148 free: total number of swap areas free

110788 cached Mem: the total number of swap areas buffered.

Process area information description:

PID: process ID

USER: process owner

PR: process priority

NI: nice value. Negative values indicate high priority; positive values indicate low priority

VIRT: the total amount of virtual memory used by the process, in Kb,VITR=SWAP+RES

RES: the amount of physical memory used by the process that has not been swapped out, in KB,RES=CODE+DATA

SHR: shared memory size (in Kb)

S: process statu

% CPU: percentage of CPU time war since last update

% MEM: percentage of physical memory used by the process

Total CPU time used by the TIME+: process (in 100 seconds)

COMMAND: command name / command line

7.2. Statically view the current process status

[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]

... .

Common parameters:

-a: a process that contains all terminals

-u: displays the owner of the process

-x: displays processes that do not belong to any terminal

-f: displays the parent-child relationship of the process

7.3. View the process tree

[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. Foreground and backstage (fg&bg)

Example: copy / usr to / tmp, because it takes a long time to copy, call to the background to copy. And then call it to the front desk. Pause again during the period, call to the background, and finally kill the process.

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

[1] 3991

/ / start replication, & execute for the background

[root@ freeit ~] # jobs

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

/ / View the actions performed in the background

[root@ freeit ~] # fg 1

Cp-I-r / usr / tmp/

/ / call to the foreground to execute the process

^ Z

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

/ / Press ctrl+z to stop the process

[root@ freeit ~] # bg 1

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

/ / continue to call to the background for execution

[root@ freeit ~] # jobs

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

[root@ freeit ~] # kill 1

/ / end this process

[root@ freeit ~] # jobs

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

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