Kako upravljati 'Systemd' uslugama i jedinicama koristeći 'Systemctl' u Linuxu


Systemctl je systemd uslužni program koji je odgovoran za kontrolu systemd sistema i upravitelja usluga. Systemd je zbirka demona za upravljanje sistemom, uslužnih programa i biblioteka koja služi kao zamjena za System V init demon. Systemd funkcionira kao centralna platforma za upravljanje i konfiguraciju za sistem sličan UNIX-u.

U Linuxu, Ekosistem Systemd je implementiran na većinu standardne Linux distribucije uz nekoliko izuzetaka. Systemd je roditeljski proces svih drugih demona često, ali ne uvijek.

Ovaj članak ima za cilj da baci svjetlo na “Kako kontrolisati sistem i usluge” na sistemu koji pokreće systemd.

Počevši od Systemtd i Systemctl osnova

1. Prvo provjerite da li je systemd instaliran na vašem sistemu ili ne, i koja je verzija trenutno instaliranog Systemd-a?

systemctl --version

systemd 215
+PAM +AUDIT +SELINUX +IMA +SYSVINIT +LIBCRYPTSETUP +GCRYPT +ACL +XZ -SECCOMP -APPARMOR

Iz gornjeg primjera je jasno da imamo instaliranu verziju systemd 215.

2. Provjerite gdje su instalirane binarne datoteke i biblioteke systemd i systemctl.

whereis systemd 
systemd: /usr/lib/systemd /etc/systemd /usr/share/systemd /usr/share/man/man1/systemd.1.gz


whereis systemctl
systemctl: /usr/bin/systemctl /usr/share/man/man1/systemctl.1.gz

3. Provjerite da li je systemd pokrenut ili ne.

ps -eaf | grep [s]ystemd

root         1     0  0 16:27 ?        00:00:00 /usr/lib/systemd/systemd --switched-root --system --deserialize 23
root       444     1  0 16:27 ?        00:00:00 /usr/lib/systemd/systemd-journald
root       469     1  0 16:27 ?        00:00:00 /usr/lib/systemd/systemd-udevd
root       555     1  0 16:27 ?        00:00:00 /usr/lib/systemd/systemd-logind
dbus       556     1  0 16:27 ?        00:00:00 /bin/dbus-daemon --system --address=systemd: --nofork --nopidfile --systemd-activation

Napomena: systemd radi kao nadređeni demon (PID=1). U gornjoj naredbi ps sa (-e) odaberite sve procese, (-a) odaberite sve procese osim vođa sesije i ( -f) za popis u punom formatu (tj. -eaf).

Također, obratite pažnju na uglaste zagrade u gornjem primjeru i ostale primjere koji slijede. Izraz uglastih zagrada dio je podudaranja obrasca klase znakova grep.

4. Analizirajte systemd proces pokretanja.

systemd-analyze
Startup finished in 487ms (kernel) + 2.776s (initrd) + 20.229s (userspace) = 23.493s

5. Analizirajte vrijeme potrebno za svaki proces pri pokretanju.

systemd-analyze blame

8.565s mariadb.service
7.991s webmin.service
6.095s postfix.service
4.311s httpd.service
3.926s firewalld.service
3.780s kdump.service
3.238s tuned.service
1.712s network.service
1.394s lvm2-monitor.service
1.126s systemd-logind.service
....

6. Analizirajte kritični lanac pri pokretanju.

systemd-analyze critical-chain

The time after the unit is active or started is printed after the "@" character.
The time the unit takes to start is printed after the "+" character.

multi-user.target @20.222s
└─mariadb.service @11.657s +8.565s
  └─network.target @11.168s
    └─network.service @9.456s +1.712s
      └─NetworkManager.service @8.858s +596ms
        └─firewalld.service @4.931s +3.926s
          └─basic.target @4.916s
            └─sockets.target @4.916s
              └─dbus.socket @4.916s
                └─sysinit.target @4.905s
                  └─systemd-update-utmp.service @4.864s +39ms
                    └─auditd.service @4.563s +301ms
                      └─systemd-tmpfiles-setup.service @4.485s +69ms
                        └─rhel-import-state.service @4.342s +142ms
                          └─local-fs.target @4.324s
                            └─boot.mount @4.286s +31ms
                              └─systemd-fsck@dev-disk-by\x2duuid-79f594ad\x2da332\x2d4730\x2dbb5f\x2d85d19608096
                                └─dev-disk-by\x2duuid-79f594ad\x2da332\x2d4730\x2dbb5f\x2d85d196080964.device @4

Važno: Systemctl prihvata usluge (.service), tačku montiranja (.mount), utičnice ( >.utičnica) i uređaji (.uređaj) kao jedinice.

7. Navedite sve dostupne jedinice.

systemctl list-unit-files

UNIT FILE                                   STATE   
proc-sys-fs-binfmt_misc.automount           static  
dev-hugepages.mount                         static  
dev-mqueue.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
brandbot.path                               disabled
.....

8. Navedite sve aktivne jedinice.

systemctl list-units

UNIT                                        LOAD   ACTIVE SUB       DESCRIPTION
proc-sys-fs-binfmt_misc.automount           loaded active waiting   Arbitrary Executable File Formats File Syste
sys-devices-pc...0-1:0:0:0-block-sr0.device loaded active plugged   VBOX_CD-ROM
sys-devices-pc...:00:03.0-net-enp0s3.device loaded active plugged   PRO/1000 MT Desktop Adapter
sys-devices-pc...00:05.0-sound-card0.device loaded active plugged   82801AA AC'97 Audio Controller
sys-devices-pc...:0:0-block-sda-sda1.device loaded active plugged   VBOX_HARDDISK
sys-devices-pc...:0:0-block-sda-sda2.device loaded active plugged   LVM PV Qzyo3l-qYaL-uRUa-Cjuk-pljo-qKtX-VgBQ8
sys-devices-pc...0-2:0:0:0-block-sda.device loaded active plugged   VBOX_HARDDISK
sys-devices-pl...erial8250-tty-ttyS0.device loaded active plugged   /sys/devices/platform/serial8250/tty/ttyS0
sys-devices-pl...erial8250-tty-ttyS1.device loaded active plugged   /sys/devices/platform/serial8250/tty/ttyS1
sys-devices-pl...erial8250-tty-ttyS2.device loaded active plugged   /sys/devices/platform/serial8250/tty/ttyS2
sys-devices-pl...erial8250-tty-ttyS3.device loaded active plugged   /sys/devices/platform/serial8250/tty/ttyS3
sys-devices-virtual-block-dm\x2d0.device    loaded active plugged   /sys/devices/virtual/block/dm-0
sys-devices-virtual-block-dm\x2d1.device    loaded active plugged   /sys/devices/virtual/block/dm-1
sys-module-configfs.device                  loaded active plugged   /sys/module/configfs
...

9. Navedite sve neispravne jedinice.

systemctl --failed

UNIT          LOAD   ACTIVE SUB    DESCRIPTION
kdump.service loaded failed failed Crash recovery kernel arming

LOAD   = Reflects whether the unit definition was properly loaded.
ACTIVE = The high-level unit activation state, i.e. generalization of SUB.
SUB    = The low-level unit activation state, values depend on unit type.

1 loaded units listed. Pass --all to see loaded but inactive units, too.
To show all installed unit files use 'systemctl list-unit-files'.

10. Provjerite da li je jedinica (cron.service) omogućena ili ne?.

systemctl is-enabled crond.service

enabled

11. Provjerite radi li jedinica ili usluga ili ne?.

systemctl status firewalld.service

firewalld.service - firewalld - dynamic firewall daemon
   Loaded: loaded (/usr/lib/systemd/system/firewalld.service; enabled)
   Active: active (running) since Tue 2015-04-28 16:27:55 IST; 34min ago
 Main PID: 549 (firewalld)
   CGroup: /system.slice/firewalld.service
           └─549 /usr/bin/python -Es /usr/sbin/firewalld --nofork --nopid

Apr 28 16:27:51 tecmint systemd[1]: Starting firewalld - dynamic firewall daemon...
Apr 28 16:27:55 tecmint systemd[1]: Started firewalld - dynamic firewall daemon.

Kontrola i upravljanje uslugama pomoću Systemctl

12. Navedite sve usluge (uključujući omogućene i onemogućene).

systemctl list-unit-files --type=service

UNIT FILE                                   STATE   
arp-ethers.service                          disabled
auditd.service                              enabled 
[email                              disabled
blk-availability.service                    disabled
brandbot.service                            static  
collectd.service                            disabled
console-getty.service                       disabled
console-shell.service                       disabled
cpupower.service                            disabled
crond.service                               enabled 
dbus-org.fedoraproject.FirewallD1.service   enabled 
....

13. Kako da pokrenem, ponovo pokrenem, zaustavim, ponovo učitam i provjerim status usluge (httpd.service) u Linuxu.

systemctl start httpd.service
systemctl restart httpd.service
systemctl stop httpd.service
systemctl reload httpd.service
systemctl status httpd.service

httpd.service - The Apache HTTP Server
   Loaded: loaded (/usr/lib/systemd/system/httpd.service; enabled)
   Active: active (running) since Tue 2015-04-28 17:21:30 IST; 6s ago
  Process: 2876 ExecStop=/bin/kill -WINCH ${MAINPID} (code=exited, status=0/SUCCESS)
 Main PID: 2881 (httpd)
   Status: "Processing requests..."
   CGroup: /system.slice/httpd.service
           ├─2881 /usr/sbin/httpd -DFOREGROUND
           ├─2884 /usr/sbin/httpd -DFOREGROUND
           ├─2885 /usr/sbin/httpd -DFOREGROUND
           ├─2886 /usr/sbin/httpd -DFOREGROUND
           ├─2887 /usr/sbin/httpd -DFOREGROUND
           └─2888 /usr/sbin/httpd -DFOREGROUND

Apr 28 17:21:30 tecmint systemd[1]: Starting The Apache HTTP Server...
Apr 28 17:21:30 tecmint httpd[2881]: AH00558: httpd: Could not reliably determine the server's fully q...ssage
Apr 28 17:21:30 tecmint systemd[1]: Started The Apache HTTP Server.
Hint: Some lines were ellipsized, use -l to show in full.

Napomena: Kada koristimo komande kao što su start, restart, stop i reload with systemctl, nećemo dobiti nikakav izlaz na terminalu, jedina naredba status će ispisati izlaz.

14. Kako aktivirati uslugu i omogućiti ili onemogućiti uslugu prilikom pokretanja (automatsko pokretanje usluge pri pokretanju sistema).

systemctl is-active httpd.service
systemctl enable httpd.service
systemctl disable httpd.service

15. Kako maskirati (onemogućava pokretanje) ili demaskirati uslugu (httpd.service).

systemctl mask httpd.service
ln -s '/dev/null' '/etc/systemd/system/httpd.service'

systemctl unmask httpd.service
rm '/etc/systemd/system/httpd.service'

16. Kako ubiti uslugu koristeći systemctl komandu.

systemctl kill httpd
systemctl status httpd

httpd.service - The Apache HTTP Server
   Loaded: loaded (/usr/lib/systemd/system/httpd.service; enabled)
   Active: failed (Result: exit-code) since Tue 2015-04-28 18:01:42 IST; 28min ago
 Main PID: 2881 (code=exited, status=0/SUCCESS)
   Status: "Total requests: 0; Current requests/sec: 0; Current traffic:   0 B/sec"

Apr 28 17:37:29 tecmint systemd[1]: httpd.service: Got notification message from PID 2881, but recepti...bled.
Apr 28 17:37:29 tecmint systemd[1]: httpd.service: Got notification message from PID 2881, but recepti...bled.
Apr 28 17:37:39 tecmint systemd[1]: httpd.service: Got notification message from PID 2881, but recepti...bled.
Apr 28 17:37:39 tecmint systemd[1]: httpd.service: Got notification message from PID 2881, but recepti...bled.
Apr 28 17:37:49 tecmint systemd[1]: httpd.service: Got notification message from PID 2881, but recepti...bled.
Apr 28 17:37:49 tecmint systemd[1]: httpd.service: Got notification message from PID 2881, but recepti...bled.
Apr 28 17:37:59 tecmint systemd[1]: httpd.service: Got notification message from PID 2881, but recepti...bled.
Apr 28 17:37:59 tecmint systemd[1]: httpd.service: Got notification message from PID 2881, but recepti...bled.
Apr 28 18:01:42 tecmint systemd[1]: httpd.service: control process exited, code=exited status=226
Apr 28 18:01:42 tecmint systemd[1]: Unit httpd.service entered failed state.
Hint: Some lines were ellipsized, use -l to show in full.

Kontrolirajte i upravljajte tačkama montiranja koristeći Systemctl

17. Navedite sve sistemske tačke postavljanja.

systemctl list-unit-files --type=mount

UNIT FILE                     STATE   
dev-hugepages.mount           static  
dev-mqueue.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

18. Kako mogu montirati, demontirati, ponovo montirati, ponovo učitati sistemske tačke montiranja i provjeriti status tačaka montiranja na sistemu?

systemctl start tmp.mount
systemctl stop tmp.mount
systemctl restart tmp.mount
systemctl reload tmp.mount
systemctl status tmp.mount

tmp.mount - Temporary Directory
   Loaded: loaded (/usr/lib/systemd/system/tmp.mount; disabled)
   Active: active (mounted) since Tue 2015-04-28 17:46:06 IST; 2min 48s ago
    Where: /tmp
     What: tmpfs
     Docs: man:hier(7)
           http://www.freedesktop.org/wiki/Software/systemd/APIFileSystems
  Process: 3908 ExecMount=/bin/mount tmpfs /tmp -t tmpfs -o mode=1777,strictatime (code=exited, status=0/SUCCESS)

Apr 28 17:46:06 tecmint systemd[1]: Mounting Temporary Directory...
Apr 28 17:46:06 tecmint systemd[1]: tmp.mount: Directory /tmp to mount over is not empty, mounting anyway.
Apr 28 17:46:06 tecmint systemd[1]: Mounted Temporary Directory.

19. Kako aktivirati, omogućiti ili onemogućiti tačku montiranja u vrijeme pokretanja (automatsko montiranje pri pokretanju sistema).

systemctl is-active tmp.mount
systemctl enable tmp.mount
systemctl disable  tmp.mount

20. Kako maskirati (onemogućava pokretanje) ili demaskirati tačku montiranja u Linuxu.

systemctl mask tmp.mount

ln -s '/dev/null' '/etc/systemd/system/tmp.mount'

systemctl unmask tmp.mount

rm '/etc/systemd/system/tmp.mount'

Kontrolirajte i upravljajte utičnicama koristeći Systemctl

21. Navedite sve dostupne sistemske utičnice.

systemctl list-unit-files --type=socket

UNIT FILE                    STATE   
dbus.socket                  static  
dm-event.socket              enabled 
lvm2-lvmetad.socket          enabled 
rsyncd.socket                disabled
sshd.socket                  disabled
syslog.socket                static  
systemd-initctl.socket       static  
systemd-journald.socket      static  
systemd-shutdownd.socket     static  
systemd-udevd-control.socket static  
systemd-udevd-kernel.socket  static  

11 unit files listed.

22. Kako da pokrenem, ponovo pokrenem, zaustavim, ponovo učitam i provjerim status utičnice (primjer: cups.socket) u Linuxu.

systemctl start cups.socket
systemctl restart cups.socket
systemctl stop cups.socket
systemctl reload cups.socket
systemctl status cups.socket

cups.socket - CUPS Printing Service Sockets
   Loaded: loaded (/usr/lib/systemd/system/cups.socket; enabled)
   Active: active (listening) since Tue 2015-04-28 18:10:59 IST; 8s ago
   Listen: /var/run/cups/cups.sock (Stream)

Apr 28 18:10:59 tecmint systemd[1]: Starting CUPS Printing Service Sockets.
Apr 28 18:10:59 tecmint systemd[1]: Listening on CUPS Printing Service Sockets.

23. Kako aktivirati utičnicu i omogućiti ili onemogućiti pri pokretanju (autostart socket pri pokretanju sistema).

systemctl is-active cups.socket
systemctl enable cups.socket
systemctl disable cups.socket

24. Kako maskirati (onemogućava pokretanje) ili demaskirati utičnicu (caps.socket).

systemctl mask cups.socket
ln -s '/dev/null' '/etc/systemd/system/cups.socket'

systemctl unmask cups.socket
rm '/etc/systemd/system/cups.socket'