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====== systemd (esercitazione) ======

Esercitazioni sul modulo **systemd**.

==== Parte 1: Visualizzazione dello stato del sistema e proprieta' delle units ====

  - Visualizzazione dello stato del sistema. <code>
[root@localhost ~]# systemctl status
● localhost.localdomain
    State: degraded
     Jobs: 0 queued
   Failed: 1 units
    Since: Mon 2018-11-26 07:22:35 EST; 22min ago
...
             │   └─1281 /sbin/agetty --noclear tty1 linux
             └─systemd-journald.service
               └─459 /usr/lib/systemd/systemd-journald
[root@localhost ~]# 
</code>
  - Identificazione della unit che ha fallito (a dopo la soluzione del problema) <code>
root@localhost ~]# systemctl list-units --failed
  UNIT         LOAD   ACTIVE SUB    DESCRIPTION
● rngd.service loaded failed failed Hardware RNG Entropy Gatherer Daemon

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'.
[root@localhost ~]# systemctl status rngd
● rngd.service - Hardware RNG Entropy Gatherer Daemon
   Loaded: loaded (/usr/lib/systemd/system/rngd.service; enabled; vendor preset: enabled)
   Active: failed (Result: exit-code) since Mon 2018-11-26 07:22:55 EST; 23min ago
  Process: 760 ExecStart=/sbin/rngd -f (code=exited, status=1/FAILURE)
 Main PID: 760 (code=exited, status=1/FAILURE)

Nov 26 07:22:51 localhost.localdomain systemd[1]: Started Hardware RNG Entropy Gatherer Daemon.
Nov 26 07:22:51 localhost.localdomain systemd[1]: Starting Hardware RNG Entropy Gatherer Daemon...
Nov 26 07:22:51 localhost.localdomain rngd[760]: Failed to init entropy source 0: Hardware RNG Device
Nov 26 07:22:51 localhost.localdomain rngd[760]: Failed to init entropy source 1: TPM RNG Device
Nov 26 07:22:51 localhost.localdomain rngd[760]: Failed to init entropy source 2: Intel RDRAND Instruction RNG
Nov 26 07:22:51 localhost.localdomain rngd[760]: can't open any entropy source
Nov 26 07:22:51 localhost.localdomain rngd[760]: Maybe RNG device modules are not loaded
Nov 26 07:22:55 localhost.localdomain systemd[1]: rngd.service: main process exited, code=exited, status=1/FAILURE
Nov 26 07:22:55 localhost.localdomain systemd[1]: Unit rngd.service entered failed state.
Nov 26 07:22:55 localhost.localdomain systemd[1]: rngd.service failed.
[root@localhost ~]# 
</code>
  - Visualizzazione di tutte le unit ed identificazione di eventuali problemi (units not found).\\ Le unit **not found** sono unit non installate (no unit file) ma presenti in dipendenze di altre unit<code>
[root@localhost ~]# systemctl list-units -a
  UNIT                                                                  LOAD      ACTIVE   SUB       DESCRIPTION
  proc-sys-fs-binfmt_misc.automount                                     loaded    active   waiting   Arbitrary Executable File Formats File System Automount Point
  dev-block-8:2.device                                                  loaded    active   plugged   LVM PV AAHlBZ-3dLf-gVNY-C5eK-ksMU-dAvH-0L6awx on /dev/sda2 2
...
  vmtoolsd.service                                                      loaded    inactive dead      Service for virtual machines hosted on VMware
● ypbind.service                                                        not-found inactive dead      ypbind.service
● yppasswdd.service                                                     not-found inactive dead      yppasswdd.service
● ypserv.service                                                        not-found inactive dead      ypserv.service
● ypxfrd.service                                                        not-found inactive dead      ypxfrd.service
...
</code>
  - Verificare che la unit ypbind.service non e' installata (visualizzare stato e unit file)<code>
[root@localhost ~]# systemctl status ypbind.service
Unit ypbind.service could not be found.
[root@localhost ~]# 
</code>
  - Cercare la unit che riporta ypbind.service tra le sue dipendenze <code>
[root@localhost ~]# systemctl list-dependencies --after ypbind.service
ypbind.service
● └─rhel-domainname.service
[root@localhost ~]# 
</code>

==== Parte 2: Stato dei servizi: start/stop/ena/disa ====

  - Visualizzare lo stato di httpd <code>
[root@localhost ~]# systemctl status httpd
● httpd.service - The Apache HTTP Server
   Loaded: loaded (/usr/lib/systemd/system/httpd.service; disabled; vendor preset: disabled)
   Active: inactive (dead)
     Docs: man:httpd(8)
           man:apachectl(8)
[root@localhost ~]# 
</code>
  - Far partire httpd, e visualizzare il suo stato <code>
[root@localhost ~]# systemctl start httpd
[root@localhost ~]# systemctl status httpd
● httpd.service - The Apache HTTP Server
   Loaded: loaded (/usr/lib/systemd/system/httpd.service; disabled; vendor preset: disabled)
   Active: active (running) since Mon 2018-11-26 07:52:25 EST; 1s ago
     Docs: man:httpd(8)
           man:apachectl(8)
 Main PID: 2248 (httpd)
   Status: "Processing requests..."
    Tasks: 6
   CGroup: /system.slice/httpd.service
           ├─2248 /usr/sbin/httpd -DFOREGROUND
           ├─2249 /usr/sbin/httpd -DFOREGROUND
           ├─2250 /usr/sbin/httpd -DFOREGROUND
           ├─2251 /usr/sbin/httpd -DFOREGROUND
           ├─2252 /usr/sbin/httpd -DFOREGROUND
           └─2253 /usr/sbin/httpd -DFOREGROUND

Nov 26 07:52:25 localhost.localdomain systemd[1]: Starting The Apache HTTP Server...
Nov 26 07:52:25 localhost.localdomain httpd[2248]: AH00558: httpd: Could not reliably determine the server's fully qualified domain name, using localhost.l...s message
Nov 26 07:52:25 localhost.localdomain systemd[1]: Started The Apache HTTP Server.
Hint: Some lines were ellipsized, use -l to show in full.
[root@localhost ~]# 
</code>
  - Abilitare httpd e visualizzare il suo stato <code>
[root@localhost ~]# systemctl enable httpd
Created symlink from /etc/systemd/system/multi-user.target.wants/httpd.service to /usr/lib/systemd/system/httpd.service.
[root@localhost ~]# systemctl status httpd
● httpd.service - The Apache HTTP Server
   Loaded: loaded (/usr/lib/systemd/system/httpd.service; enabled; vendor preset: disabled)
   Active: active (running) since Mon 2018-11-26 07:52:25 EST; 37s ago
     Docs: man:httpd(8)
           man:apachectl(8)
 Main PID: 2248 (httpd)
   Status: "Total requests: 0; Current requests/sec: 0; Current traffic:   0 B/sec"
   CGroup: /system.slice/httpd.service
           ├─2248 /usr/sbin/httpd -DFOREGROUND
           ├─2249 /usr/sbin/httpd -DFOREGROUND
           ├─2250 /usr/sbin/httpd -DFOREGROUND
           ├─2251 /usr/sbin/httpd -DFOREGROUND
           ├─2252 /usr/sbin/httpd -DFOREGROUND
           └─2253 /usr/sbin/httpd -DFOREGROUND

Nov 26 07:52:25 localhost.localdomain systemd[1]: Starting The Apache HTTP Server...
Nov 26 07:52:25 localhost.localdomain httpd[2248]: AH00558: httpd: Could not reliably determine the server's fully qualified domain name, using localhost.l...s message
Nov 26 07:52:25 localhost.localdomain systemd[1]: Started The Apache HTTP Server.
Hint: Some lines were ellipsized, use -l to show in full.
[root@localhost ~]# 
</code>
  - Riconfigurare lo stato di abilitazione di httpd al preset <code>
[root@localhost ~]# systemctl preset httpd
Removed symlink /etc/systemd/system/multi-user.target.wants/httpd.service.
[root@localhost ~]# systemctl status httpd
● httpd.service - The Apache HTTP Server
   Loaded: loaded (/usr/lib/systemd/system/httpd.service; disabled; vendor preset: disabled)
   Active: active (running) since Mon 2018-11-26 07:52:25 EST; 1min 37s ago
     Docs: man:httpd(8)
           man:apachectl(8)
 Main PID: 2248 (httpd)
   Status: "Total requests: 0; Current requests/sec: 0; Current traffic:   0 B/sec"
   CGroup: /system.slice/httpd.service
           ├─2248 /usr/sbin/httpd -DFOREGROUND
           ├─2249 /usr/sbin/httpd -DFOREGROUND
           ├─2250 /usr/sbin/httpd -DFOREGROUND
           ├─2251 /usr/sbin/httpd -DFOREGROUND
           ├─2252 /usr/sbin/httpd -DFOREGROUND
           └─2253 /usr/sbin/httpd -DFOREGROUND

Nov 26 07:52:25 localhost.localdomain systemd[1]: Starting The Apache HTTP Server...
Nov 26 07:52:25 localhost.localdomain httpd[2248]: AH00558: httpd: Could not reliably determine the server's fully qualified domain name, using localhost.l...s message
Nov 26 07:52:25 localhost.localdomain systemd[1]: Started The Apache HTTP Server.
Hint: Some lines were ellipsized, use -l to show in full.
[root@localhost ~]# systemctl stop httpd
[root@localhost ~]# systemctl status httpd
● httpd.service - The Apache HTTP Server
   Loaded: loaded (/usr/lib/systemd/system/httpd.service; disabled; vendor preset: disabled)
   Active: inactive (dead)
     Docs: man:httpd(8)
           man:apachectl(8)

Nov 26 07:52:25 localhost.localdomain systemd[1]: Starting The Apache HTTP Server...
Nov 26 07:52:25 localhost.localdomain httpd[2248]: AH00558: httpd: Could not reliably determine the server's fully qualified domain name, using localhost.l...s message
Nov 26 07:52:25 localhost.localdomain systemd[1]: Started The Apache HTTP Server.
Nov 26 07:54:10 localhost.localdomain systemd[1]: Stopping The Apache HTTP Server...
Nov 26 07:54:11 localhost.localdomain systemd[1]: Stopped The Apache HTTP Server.
Hint: Some lines were ellipsized, use -l to show in full.
[root@localhost ~]# 
</code>

==== Parte 3: target units ====

  - Visualizzare la default target unit <code>
[root@localhost ~]# systemctl get-default 
multi-user.target
[root@localhost ~]# 
</code>
  - Visualizzare le dipendenze di multi-target dirette e inverse <code>
[root@localhost ~]# systemctl list-dependencies multi-user.target
multi-user.target
● ├─abrt-ccpp.service
● ├─abrt-oops.service
● ├─abrt-vmcore.service
...
[root@localhost ~]# systemctl list-dependencies multi-user.target --reverse
multi-user.target
● └─graphical.target
[root@localhost ~]# 
</code>
  - Visualizzare la lista di link delle unit //wanted// da multi-user.target <code>
[root@localhost ~]# ls -l -1 /etc/systemd/system/multi-user.target.wants/
total 0
lrwxrwxrwx. 1 root root 41 Nov 13 08:00 abrt-ccpp.service -> /usr/lib/systemd/system/abrt-ccpp.service
lrwxrwxrwx. 1 root root 37 Nov 13 08:00 abrtd.service -> /usr/lib/systemd/system/abrtd.service
lrwxrwxrwx. 1 root root 41 Nov 13 08:00 abrt-oops.service -> /usr/lib/systemd/system/abrt-oops.service
...
[root@localhost ~]# ls -l -1 /lib/systemd/system/multi-user.target.wants/
total 0
lrwxrwxrwx. 1 root root 15 Nov 13 05:55 dbus.service -> ../dbus.service
lrwxrwxrwx. 1 root root 15 Nov 13 07:54 getty.target -> ../getty.target
lrwxrwxrwx. 1 root root 24 Nov 13 05:55 plymouth-quit.service -> ../plymouth-quit.service
lrwxrwxrwx. 1 root root 29 Nov 13 05:55 plymouth-quit-wait.service -> ../plymouth-quit-wait.service
lrwxrwxrwx. 1 root root 33 Nov 13 07:54 systemd-ask-password-wall.path -> ../systemd-ask-password-wall.path
</code>
  - Andare in graphical target <code>
[root@localhost ~]# systemctl isolate graphical.target
[root@localhost ~]# 
</code>
  - Creare una snapshot con httpd e mysqld attivi <code>
[root@localhost ~]# systemctl start httpd
[root@localhost ~]# systemctl start mariadb.service 
[root@localhost ~]# systemctl snapshot snap1
snap1.snapshot
[root@localhost ~]# 
</code>
  - Spostarsi tra multi-user target e snapshot e verificare che i servizi si attivano e disattivano <code>
[root@localhost ~]# systemctl isolate multi-user
[root@localhost ~]# systemctl status httpd
● httpd.service - The Apache HTTP Server
   Loaded: loaded (/usr/lib/systemd/system/httpd.service; disabled; vendor preset: disabled)
   Active: inactive (dead) since Mon 2018-11-26 14:00:02 CET; 5s ago
     Docs: man:httpd(8)
           man:apachectl(8)
  Process: 3446 ExecStop=/bin/kill -WINCH ${MAINPID} (code=exited, status=0/SUCCESS)
  Process: 2903 ExecStart=/usr/sbin/httpd $OPTIONS -DFOREGROUND (code=exited, status=0/SUCCESS)
 Main PID: 2903 (code=exited, status=0/SUCCESS)
   Status: "Total requests: 0; Current requests/sec: 0; Current traffic:   0 B/sec"

Nov 26 13:58:14 localhost.localdomain systemd[1]: Starting The Apache HTTP Server...
Nov 26 13:58:14 localhost.localdomain httpd[2903]: AH00558: httpd: Could not reliably determine the server's fully qualified domain name, using localhost.l...s message
Nov 26 13:58:14 localhost.localdomain systemd[1]: Started The Apache HTTP Server.
Nov 26 14:00:01 localhost.localdomain systemd[1]: Stopping The Apache HTTP Server...
Nov 26 14:00:02 localhost.localdomain systemd[1]: Stopped The Apache HTTP Server.
Hint: Some lines were ellipsized, use -l to show in full.
[root@localhost ~]# systemctl status mariadb
● mariadb.service - MariaDB database server
   Loaded: loaded (/usr/lib/systemd/system/mariadb.service; disabled; vendor preset: disabled)
   Active: inactive (dead) since Mon 2018-11-26 14:00:05 CET; 9s ago
  Process: 3199 ExecStartPost=/usr/libexec/mariadb-wait-ready $MAINPID (code=exited, status=0/SUCCESS)
  Process: 3198 ExecStart=/usr/bin/mysqld_safe --basedir=/usr (code=exited, status=0/SUCCESS)
  Process: 3119 ExecStartPre=/usr/libexec/mariadb-prepare-db-dir %n (code=exited, status=0/SUCCESS)
 Main PID: 3198 (code=exited, status=0/SUCCESS)

Nov 26 13:58:54 localhost.localdomain mariadb-prepare-db-dir[3119]: The latest information about MariaDB is available at http://mariadb.org/.
Nov 26 13:58:54 localhost.localdomain mariadb-prepare-db-dir[3119]: You can find additional information about the MySQL part at:
Nov 26 13:58:54 localhost.localdomain mariadb-prepare-db-dir[3119]: http://dev.mysql.com
Nov 26 13:58:54 localhost.localdomain mariadb-prepare-db-dir[3119]: Consider joining MariaDB's strong and vibrant community:
Nov 26 13:58:54 localhost.localdomain mariadb-prepare-db-dir[3119]: https://mariadb.org/get-involved/
Nov 26 13:58:54 localhost.localdomain mysqld_safe[3198]: 181126 13:58:54 mysqld_safe Logging to '/var/log/mariadb/mariadb.log'.
Nov 26 13:58:54 localhost.localdomain mysqld_safe[3198]: 181126 13:58:54 mysqld_safe Starting mysqld daemon with databases from /var/lib/mysql
Nov 26 13:58:56 localhost.localdomain systemd[1]: Started MariaDB database server.
Nov 26 14:00:01 localhost.localdomain systemd[1]: Stopping MariaDB database server...
Nov 26 14:00:05 localhost.localdomain systemd[1]: Stopped MariaDB database server.
[root@localhost ~]# systemctl isolate snap1.snapshot
[root@localhost ~]# systemctl status httpd
● httpd.service - The Apache HTTP Server
   Loaded: loaded (/usr/lib/systemd/system/httpd.service; disabled; vendor preset: disabled)
   Active: active (running) since Mon 2018-11-26 14:03:21 CET; 8s ago
     Docs: man:httpd(8)
           man:apachectl(8)
  Process: 3446 ExecStop=/bin/kill -WINCH ${MAINPID} (code=exited, status=0/SUCCESS)
 Main PID: 3583 (httpd)
   Status: "Processing requests..."
    Tasks: 6
   CGroup: /system.slice/httpd.service
           ├─3583 /usr/sbin/httpd -DFOREGROUND
           ├─3644 /usr/sbin/httpd -DFOREGROUND
           ├─3645 /usr/sbin/httpd -DFOREGROUND
           ├─3646 /usr/sbin/httpd -DFOREGROUND
           ├─3647 /usr/sbin/httpd -DFOREGROUND
           └─3648 /usr/sbin/httpd -DFOREGROUND

Nov 26 14:03:21 localhost.localdomain systemd[1]: Starting The Apache HTTP Server...
Nov 26 14:03:21 localhost.localdomain httpd[3583]: AH00558: httpd: Could not reliably determine the server's fully qualified domain name, using localhost.l...s message
Nov 26 14:03:21 localhost.localdomain systemd[1]: Started The Apache HTTP Server.
Hint: Some lines were ellipsized, use -l to show in full.
[root@localhost ~]# 
</code>
  - Andare in default target e rimuovere la snapshot <code>
[root@localhost ~]# systemctl default
[root@localhost ~]# systemctl delete snap1.snapshot
[root@localhost ~]# 
</code>

==== Parte 4: unit files ====

In /root/ses c'e' una applicazione che implementa un servizio (Simple Echo Service) che si mette in ascolto
sulla porta TCP 0.0.0.0:5555.\\
Provate ad eseguirlo interattivamente:\\
su una finestra eseguite: **# /root/ses/ses**\\
su una seconda finestra eseguite **# telnet 127.0.0.1 5555**\\

L'esercitazione consiste nei seguenti punti:

  - Creare uno unit file per far eseguire ses tramite systemd (includere configuraizone per fare restart in 30 secondi) <code>
[root@localhost ses]# cat ses.service 
[Unit]
Description=SES Simple Echo Service

# needed?
#Wants=ses.socket
#After=ses.socket

[Service]
Type=simple
ExecStart=/root/ses/ses
Restart=always
RestartSec=30s

#[Install]
#WantedBy=multi-user.target

[root@localhost ses]# cp ses.service /etc/systemd/system/
[root@localhost ses]# systemctl status ses
● ses.service - SES Simple Echo Service
   Loaded: loaded (/etc/systemd/system/ses.service; static; vendor preset: disabled)
   Active: inactive (dead)

Nov 26 14:14:32 localhost.localdomain systemd[1]: [/etc/systemd/system/ses.service:1] Assignment outside of section. Ignoring.
Nov 26 14:14:32 localhost.localdomain systemd[1]: [/etc/systemd/system/ses.service:18] Missing '='.
Nov 26 14:16:23 localhost.localdomain systemd[1]: [/etc/systemd/system/ses.service:1] Assignment outside of section. Ignoring.
[root@localhost ses]# netstat -nap | grep 5555
[root@localhost ses]# systemctl start ses
[root@localhost ses]# netstat -nap | grep 5555
tcp        0      0 0.0.0.0:5555            0.0.0.0:*               LISTEN      4603/ses            
[root@localhost ses]# </code><code>
[root@localhost ~]# telnet 127.0.0.1 5555
Trying 127.0.0.1...
Connected to 127.0.0.1.
Escape character is '^]'.
Welcome to the Simple Echo Service. Type "quit" to close connection, "bigquit" to quit the service.
ciao
ciao
bigquit
Connection closed by foreign host. </code><code>

</code>
  - Creare unit files per far eseguire ses da systemd tramite socket-based activation <code>
[root@localhost ~]# cat ses.socket
[Unit]
Description=Simple Echo Server Activation Socket

[Socket]
ListenStream=0.0.0.0:5555

[Install]
WantedBy=sockets.target

[root@localhost ~]# cat ses.service
[Unit]
Description=SES Simple Echo Service

# needed?
Wants=ses.socket
After=ses.socket

[Service]
Type=simple
ExecStart=/root/ses/ses

#[Install]
#WantedBy=multi-user.target
[root@localhost ~]# cp -f ses.socket ses.service /etc/systemd/system/
cp: overwrite ‘/etc/systemd/system/ses.service’? y
[root@localhost ~]# systemctl status ses.socket 
● ses.socket - Simple Echo Server Activation Socket
   Loaded: loaded (/etc/systemd/system/ses.socket; disabled; vendor preset: disabled)
   Active: inactive (dead)
   Listen: 0.0.0.0:5555 (Stream)
[root@localhost ~]# systemctl enable ses.socket
Created symlink from /etc/systemd/system/sockets.target.wants/ses.socket to /etc/systemd/system/ses.socket.
[root@localhost ~]# systemctl start ses.socket
[root@localhost ~]# systemctl status ses.socket 
● ses.socket - Simple Echo Server Activation Socket
   Loaded: loaded (/etc/systemd/system/ses.socket; enabled; vendor preset: disabled)
   Active: active (listening) since Mon 2018-11-26 16:50:55 CET; 4s ago
   Listen: 0.0.0.0:5555 (Stream)

Nov 26 16:50:55 localhost.localdomain systemd[1]: Listening on Simple Echo Server Activation Socket.
Nov 26 16:50:55 localhost.localdomain systemd[1]: Starting Simple Echo Server Activation Socket.
[root@localhost ~]# netstat -napt | grep 5555
tcp        0      0 0.0.0.0:5555            0.0.0.0:*               LISTEN      1/systemd
[root@localhost ~]# </code> <code>
[root@localhost ~]# telnet 127.0.0.1 5555
Trying 127.0.0.1...
Connected to 127.0.0.1.
Escape character is '^]'.
Welcome to the Simple Echo Service. Type "quit" to close connection, "bigquit" to quit the service.
</code><code>
[root@localhost ~]# netstat -napt | grep 5555
tcp        0      0 0.0.0.0:5555            0.0.0.0:*               LISTEN      1/systemd           
tcp        0      0 127.0.0.1:5555          127.0.0.1:41130         ESTABLISHED 15197/ses           
tcp        0      0 127.0.0.1:41130         127.0.0.1:5555          ESTABLISHED 15196/telnet        
[root@localhost ~]# systemctl status ses
● ses.service - SES Simple Echo Service
   Loaded: loaded (/etc/systemd/system/ses.service; static; vendor preset: disabled)
   Active: active (running) since Mon 2018-11-26 16:53:56 CET; 2min 34s ago
 Main PID: 15197 (ses)
    Tasks: 1
   CGroup: /system.slice/ses.service
           └─15197 /root/ses/ses

Nov 26 16:53:56 localhost.localdomain systemd[1]: Started SES Simple Echo Service.
Nov 26 16:53:56 localhost.localdomain systemd[1]: Starting SES Simple Echo Service...
[root@localhost ~]# 
</code>
  - Creare uno unit file per far eseguire ses da systemd tramite path-based activation <code>
[root@localhost ses]# cat ses.service
[Unit]
Description=SES Simple Echo Service

[Service]
Type=simple
ExecStart=/root/ses/ses

[root@localhost ses]# cat ses.path
[Unit]
Description=Simple Echo Server Activation Path

[Path]
PathExists=/root/ses/activate

[root@localhost ses]# cp ses.service ses.path /etc/systemd/system/
[root@localhost ses]# systemctl status ses.path
● ses.path - Simple Echo Server Activation Path
   Loaded: loaded (/etc/systemd/system/ses.path; static; vendor preset: disabled)
   Active: inactive (dead)
[root@localhost ses]# systemctl start ses.path
[root@localhost ses]# systemctl status ses.path
● ses.path - Simple Echo Server Activation Path
   Loaded: loaded (/etc/systemd/system/ses.path; static; vendor preset: disabled)
   Active: active (waiting) since Mon 2018-11-26 17:07:41 CET; 2s ago

Nov 26 17:07:41 localhost.localdomain systemd[1]: Started Simple Echo Server Activation Path.
Nov 26 17:07:41 localhost.localdomain systemd[1]: Starting Simple Echo Server Activation Path.
[root@localhost ses]# systemctl status ses.service
● ses.service - SES Simple Echo Service
   Loaded: loaded (/etc/systemd/system/ses.service; static; vendor preset: disabled)
   Active: inactive (dead) since Mon 2018-11-26 16:57:06 CET; 11min ago
...
[root@localhost ses]# netstat -napt | grep 5555
[root@localhost ses]# touch /root/ses/activate
[root@localhost ses]# netstat -napt | grep 5555
tcp        0      0 0.0.0.0:5555            0.0.0.0:*               LISTEN      15562/ses           
[root@localhost ses]# systemctl status ses.service
● ses.service - SES Simple Echo Service
   Loaded: loaded (/etc/systemd/system/ses.service; static; vendor preset: disabled)
   Active: active (running) since Mon 2018-11-26 17:09:40 CET; 6s ago
 Main PID: 15562 (ses)
    Tasks: 1
   CGroup: /system.slice/ses.service
           └─15562 /root/ses/ses

Nov 26 17:09:40 localhost.localdomain systemd[1]: Started SES Simple Echo Service.
Nov 26 17:09:40 localhost.localdomain systemd[1]: Starting SES Simple Echo Service...
[root@localhost ses]# rm /root/ses/activate 
rm: remove regular empty file ‘/root/ses/activate’? y
[root@localhost ses]# systemctl status ses
● ses.service - SES Simple Echo Service
   Loaded: loaded (/etc/systemd/system/ses.service; static; vendor preset: disabled)
   Active: active (running) since Mon 2018-11-26 17:09:40 CET; 1min 20s ago
 Main PID: 15562 (ses)
    Tasks: 1
   CGroup: /system.slice/ses.service
           └─15562 /root/ses/ses

Nov 26 17:09:40 localhost.localdomain systemd[1]: Started SES Simple Echo Service.
Nov 26 17:09:40 localhost.localdomain systemd[1]: Starting SES Simple Echo Service...
</code>


==== Parte 5: journald ====

  - Visualizzare i log di journald, tutti o quelli di una particolare unit <code>
[root@localhost ~]# journalctl
-- Logs begin at Mon 2018-11-26 13:22:30 CET, end at Mon 2018-11-26 17:11:26 CET. --
Nov 26 13:22:30 localhost.localdomain systemd-journal[87]: Runtime journal is using 8.0M (max allowed 91.9M, trying to leave 137.9M free of 911.3M available → current 
Nov 26 13:22:30 localhost.localdomain kernel: Initializing cgroup subsys cpuset
...
Nov 26 17:11:26 localhost.localdomain ses[15562]: SES - Simple Echo Server started
Nov 26 17:11:26 localhost.localdomain ses[15562]: SES - Simple Echo Server has been started out of systemd.
Nov 26 17:11:26 localhost.localdomain ses[15562]: SES - Simple Echo Server is quitting
[root@localhost ~]# journalctl -u <tab><tab>
abrtd.service                      netcf-transaction.service          session-15.scope                   session-4.scope
accounts-daemon.service            NetworkManager-dispatcher.service  session-16.scope                   session-5.scope
alsa-state.service                 NetworkManager.service             session-17.scope                   session-6.scope
auditd.service                     network.service                    session-18.scope                   session-7.scope
avahi-daemon.service               packagekit.service                 session-19.scope                   session-8.scope
chronyd.service                    polkit.service                     session-1.scope                    session-9.scope
crond.service                      postfix.service                    session-20.scope                   session-c1.scope
dbus.service                       realmd.service                     session-21.scope                   session-c2.scope
fprintd.service                    rngd.service                       session-22.scope                   smartd.service
gdm.service                        rpc-statd-notify.service           session-23.scope                   sshd.service
httpd.service                      rsyslog.service                    session-24.scope                   systemd-fsck-root.service
irqbalance.service                 rtkit-daemon.service               session-25.scope                   systemd-journald.service
kdump.service                      ses.service                        session-26.scope                   systemd-logind.service
libvirtd.service                   session-10.scope                   session-27.scope                   systemd-timedated.service
lvm2-monitor.service               session-11.scope                   session-28.scope                   systemd-udevd.service
lvm2-pvscan@8:2.service            session-12.scope                   session-29.scope                   udisks2.service
mariadb.service                    session-13.scope                   session-2.scope                    
ModemManager.service               session-14.scope                   session-3.scope                    
[root@localhost ~]# journalctl -u chronyd
-- Logs begin at Mon 2018-11-26 13:22:30 CET, end at Mon 2018-11-26 17:11:26 CET. --
Nov 26 13:22:55 localhost.localdomain systemd[1]: Starting NTP client/server...
Nov 26 13:22:56 localhost.localdomain chronyd[815]: chronyd version 3.2 starting (+CMDMON +NTP +REFCLOCK +RTC +PRIVDROP +SCFILTER +SECHASH +SIGND +ASYNCDNS +IPV6 +DEBU
Nov 26 13:22:57 localhost.localdomain chronyd[815]: Frequency 24.009 +/- 2.704 ppm read from /var/lib/chrony/drift
Nov 26 13:22:57 localhost.localdomain systemd[1]: Started NTP client/server.
Nov 26 13:23:16 localhost.localdomain chronyd[815]: Selected source 193.204.114.233
...
Nov 26 16:46:11 localhost.localdomain chronyd[815]: Selected source 31.14.131.188
Nov 26 16:46:11 localhost.localdomain chronyd[815]: System clock wrong by 9959.861550 seconds, adjustment started
</code>
  - Visualizzare solo i messaggi con priority compresa tra **notice** ed **err** <code>
[root@localhost ~]# man journalctl | grep notice
           "alert" (1), "crit" (2), "err" (3), "warning" (4), "notice" (5), "info" (6), "debug" (7). If a single log level is specified, all messages with this
[root@localhost ~]# journalctl -p 3..5
-- Logs begin at Mon 2018-11-26 13:22:30 CET, end at Mon 2018-11-26 17:11:26 CET. --
Nov 26 13:22:30 localhost.localdomain kernel: Linux version 3.10.0-862.14.4.el7.x86_64 (mockbuild@kbuilder.bsys.centos.org) (gcc version 4.8.5 20150623 (Red Hat 4.8.5-
Nov 26 13:22:30 localhost.localdomain kernel: ACPI: RSDP 00000000000e0000 00024 (v02 VBOX  )
Nov 26 13:22:30 localhost.localdomain kernel: ACPI: XSDT 000000007fff0030 0003C (v01 VBOX   VBOXXSDT 00000001 ASL  00000061)
...
Nov 26 17:10:34 localhost.localdomain dbus[762]: [system] Activating via systemd: service name='org.freedesktop.nm_dispatcher' unit='dbus-org.freedesktop.nm-dispatcher
Nov 26 17:10:34 localhost.localdomain dbus[762]: [system] Successfully activated service 'org.freedesktop.nm_dispatcher'
[root@localhost ~]# 
</code>
  - Visualizzare con filtro sul transport stdout; utilizzare la completion <code>
[root@localhost ~]# journalctl <tab><tab>
_AUDIT_LOGINUID=             COREDUMP_EXE=                _MACHINE_ID=                 _SOURCE_REALTIME_TIMESTAMP=  _TRANSPORT=
_AUDIT_SESSION=              __CURSOR=                    MESSAGE=                     SYSLOG_FACILITY=             _UDEV_DEVLINK=
_BOOT_ID=                    ERRNO=                       MESSAGE_ID=                  SYSLOG_IDENTIFIER=           _UDEV_DEVNODE=
_CMDLINE=                    _EXE=                        __MONOTONIC_TIMESTAMP=       SYSLOG_PID=                  _UDEV_SYSNAME=
CODE_FILE=                   _GID=                        _PID=                        _SYSTEMD_CGROUP=             _UID=
CODE_FUNC=                   _HOSTNAME=                   PRIORITY=                    _SYSTEMD_OWNER_UID=          
CODE_LINE=                   _KERNEL_DEVICE=              __REALTIME_TIMESTAMP=        _SYSTEMD_SESSION=            
_COMM=                       _KERNEL_SUBSYSTEM=           _SELINUX_CONTEXT=            _SYSTEMD_UNIT=               
[root@localhost ~]# journalctl _TRANSPORT= <tab><tab>
driver   journal  kernel   stdout   syslog   
[root@localhost ~]# journalctl _TRANSPORT=stdout
-- Logs begin at Mon 2018-11-26 13:22:30 CET, end at Mon 2018-11-26 17:11:26 CET. --
Nov 26 13:22:32 localhost.localdomain systemd-fsck[361]: /sbin/fsck.xfs: XFS file system.
Nov 26 13:22:46 localhost.localdomain lvm[644]: WARNING: lvmetad is being updated, retrying (setup) for 10 more seconds.
Nov 26 13:22:47 localhost.localdomain lvm[467]: 2 logical volume(s) in volume group "centos" monitored
Nov 26 13:22:48 localhost.localdomain lvm[644]: 2 logical volume(s) in volume group "centos" now active
...
Nov 26 17:11:26 localhost.localdomain ses[15562]: SES - Simple Echo Server started
Nov 26 17:11:26 localhost.localdomain ses[15562]: SES - Simple Echo Server has been started out of systemd.
Nov 26 17:11:26 localhost.localdomain ses[15562]: SES - Simple Echo Server is quitting

</code>
  - Visualizzare con filtro su SYSLOG_IDENTIFIER <code>
[root@localhost ~]# journalctl SYSLOG_IDENTIFIER=sshd 
-- Logs begin at Mon 2018-11-26 13:22:30 CET, end at Mon 2018-11-26 17:20:01 CET. --
Nov 26 13:23:14 localhost.localdomain sshd[1262]: Server listening on 0.0.0.0 port 22.
Nov 26 13:23:14 localhost.localdomain sshd[1262]: Server listening on :: port 22.
Nov 26 13:43:34 localhost.localdomain sshd[2060]: Accepted password for root from 192.168.56.1 port 49217 ssh2
Nov 26 13:43:34 localhost.localdomain sshd[2060]: pam_unix(sshd:session): session opened for user root by (uid=0)
Nov 26 14:11:41 localhost.localdomain sshd[4282]: Accepted password for root from 192.168.56.1 port 49309 ssh2
Nov 26 14:11:41 localhost.localdomain sshd[4282]: pam_unix(sshd:session): session opened for user root by (uid=0)
[root@localhost ~]# 
</code>
  - Abilitare la persistenza (verificare la collocazione dei journal files) <code>
[root@localhost ~]# ls -R /run/log/journal/
/run/log/journal/:
81c211dd7e6f428995dec2e9d999c878

/run/log/journal/81c211dd7e6f428995dec2e9d999c878:
system.journal
[root@localhost ~]# ls -R /var/log/journal
ls: cannot access /var/log/journal: No such file or directory
[root@localhost ~]# mkdir /var/log/journal
[root@localhost ~]# systemctl restart systemd-journald
[root@localhost ~]# ls -R /run/log/journal/
ls: cannot access /run/log/journal/: No such file or directory
[root@localhost ~]# ls -R /var/log/journal
/var/log/journal:
81c211dd7e6f428995dec2e9d999c878

/var/log/journal/81c211dd7e6f428995dec2e9d999c878:
system.journal
[root@localhost ~]# 

</code>
  - Visualizzazione della lista di boot. Verifica della persistenza al reboot. <code>
[root@localhost ~]# journalctl --list-boots 
-1 2f4fbe37d34d42bb94a9042eba2d3f89 Mon 2018-11-26 13:22:30 CET—Mon 2018-11-26 17:25:04 CET
 0 233a251b2d3d4831b63d9ebfac6b6fb2 Mon 2018-11-26 17:12:57 CET—Mon 2018-11-26 23:01:51 CET
[root@localhost ~]# journalctl -b -1 -u postfix
-- Logs begin at Mon 2018-11-26 13:22:30 CET, end at Mon 2018-11-26 23:01:51 CET. --
Nov 26 13:23:12 localhost.localdomain systemd[1]: Starting Postfix Mail Transport Agent...
Nov 26 13:23:18 localhost.localdomain postfix/postfix-script[1464]: starting the Postfix mail system
Nov 26 13:23:18 localhost.localdomain postfix/master[1466]: daemon started -- version 2.10.1, configuration /etc/postfix
Nov 26 13:23:18 localhost.localdomain systemd[1]: Started Postfix Mail Transport Agent.
Nov 26 17:24:59 localhost.localdomain systemd[1]: Stopping Postfix Mail Transport Agent...
Nov 26 17:24:59 localhost.localdomain systemd[1]: Stopped Postfix Mail Transport Agent.
[root@localhost ~]# journalctl -b 0 -u postfix
-- Logs begin at Mon 2018-11-26 13:22:30 CET, end at Mon 2018-11-26 23:01:51 CET. --
Nov 26 17:13:40 localhost.localdomain systemd[1]: Starting Postfix Mail Transport Agent...
Nov 26 23:01:26 localhost.localdomain postfix/postfix-script[1464]: starting the Postfix mail system
Nov 26 23:01:27 localhost.localdomain postfix/master[1466]: daemon started -- version 2.10.1, configuration /etc/postfix
Nov 26 23:01:27 localhost.localdomain systemd[1]: Started Postfix Mail Transport Agent.
[root@localhost ~]# 
</code>
  - Visualizzazione dei kernel log del boot precedente <code>
[root@localhost ~]# journalctl -k -b -1
-- Logs begin at Mon 2018-11-26 13:22:30 CET, end at Mon 2018-11-26 23:01:51 CET. --
Nov 26 13:22:30 localhost.localdomain kernel: Initializing cgroup subsys cpuset
Nov 26 13:22:30 localhost.localdomain kernel: Initializing cgroup subsys cpu
...
Nov 26 17:23:25 localhost.localdomain systemd-journald[459]: Received SIGTERM from PID 1 (systemd).
Nov 26 17:25:03 localhost.localdomain kernel: Ebtables v2.0 unregistered
Nov 26 17:25:03 localhost.localdomain kernel: type=1305 audit(1543249503.313:853): audit_pid=0 old=731 auid=4294967295 ses=4294967295 res=1
...
Nov 26 17:25:03 localhost.localdomain systemd-shutdown[1]: Syncing filesystems and block devices.
Nov 26 17:25:04 localhost.localdomain systemd-shutdown[1]: Sending SIGTERM to remaining processes...
[root@localhost ~]# 

</code>
  - Visualizzazione della unit **postfix** in configurazione di persistenza (verificare la visualizzazione dei boot) <code>
[root@localhost ~]# journalctl -u postfix
-- Logs begin at Mon 2018-11-26 13:22:30 CET, end at Mon 2018-11-26 23:06:50 CET. --
Nov 26 13:23:12 localhost.localdomain systemd[1]: Starting Postfix Mail Transport Agent...
Nov 26 13:23:18 localhost.localdomain postfix/postfix-script[1464]: starting the Postfix mail system
Nov 26 13:23:18 localhost.localdomain postfix/master[1466]: daemon started -- version 2.10.1, configuration /etc/postfix
Nov 26 13:23:18 localhost.localdomain systemd[1]: Started Postfix Mail Transport Agent.
Nov 26 17:24:59 localhost.localdomain systemd[1]: Stopping Postfix Mail Transport Agent...
Nov 26 17:24:59 localhost.localdomain systemd[1]: Stopped Postfix Mail Transport Agent.
-- Reboot --
Nov 26 17:13:40 localhost.localdomain systemd[1]: Starting Postfix Mail Transport Agent...
Nov 26 23:01:26 localhost.localdomain postfix/postfix-script[1464]: starting the Postfix mail system
Nov 26 23:01:27 localhost.localdomain postfix/master[1466]: daemon started -- version 2.10.1, configuration /etc/postfix
Nov 26 23:01:27 localhost.localdomain systemd[1]: Started Postfix Mail Transport Agent.
</code>
  - Visualizzazione in follow mode\\ Per generare un messaggio di log utilizzare **logger** <code>
[root@localhost ~]# journalctl -n 5 -f
-- Logs begin at Mon 2018-11-26 13:22:30 CET. --
Nov 26 23:08:16 localhost.localdomain systemd-logind[755]: New session 3 of user root.
Nov 26 23:08:16 localhost.localdomain systemd[1]: Starting Session 3 of user root.
Nov 26 23:08:16 localhost.localdomain sshd[2028]: pam_unix(sshd:session): session opened for user root by (uid=0)
Nov 26 23:08:16 localhost.localdomain dbus[757]: [system] Activating service name='org.freedesktop.problems' (using servicehelper)
Nov 26 23:08:16 localhost.localdomain dbus[757]: [system] Successfully activated service 'org.freedesktop.problems'

</code><code>
[root@localhost ~]# logger -p user.err "logger message prio err"
[root@localhost ~]# 
</code><code>
Nov 26 23:09:13 localhost.localdomain root[2112]: logger message prio err
^C
[root@localhost ~]# 

</code>
  - Visualizzare un evento in modalita' verbose, json-pretty <code>
[root@localhost ~]# journalctl -u postfix -o verbose -n 1
-- Logs begin at Mon 2018-11-26 13:22:30 CET, end at Mon 2018-11-26 23:10:01 CET. --
Mon 2018-11-26 23:01:27.226838 CET [s=0ffb05c238394c6bb39660bc2c0b08fb;i=f90;b=233a251b2d3d4831b63d9ebfac6b6fb2;m=2f3c47b;t=57b98797ff589;x=4ed15931e599c3cf]
    PRIORITY=6
    _UID=0
    _GID=0
    _MACHINE_ID=81c211dd7e6f428995dec2e9d999c878
    _HOSTNAME=localhost.localdomain
    SYSLOG_FACILITY=3
    SYSLOG_IDENTIFIER=systemd
    CODE_FILE=src/core/job.c
    CODE_LINE=776
    CODE_FUNCTION=job_log_status_message
    MESSAGE_ID=39f53479d3a045ac8e11786248231fbf
    RESULT=done
    _TRANSPORT=journal
    _PID=1
    _COMM=systemd
    _EXE=/usr/lib/systemd/systemd
    _CAP_EFFECTIVE=1fffffffff
    _SYSTEMD_CGROUP=/
    _CMDLINE=/usr/lib/systemd/systemd --switched-root --system --deserialize 22
    UNIT=postfix.service
    MESSAGE=Started Postfix Mail Transport Agent.
    _BOOT_ID=233a251b2d3d4831b63d9ebfac6b6fb2
    _SOURCE_REALTIME_TIMESTAMP=1543269687226838
[root@localhost ~]# 
</code><code>
[root@localhost ~]# journalctl -u postfix -o json-pretty -n 1
{
        "__CURSOR" : "s=0ffb05c238394c6bb39660bc2c0b08fb;i=f90;b=233a251b2d3d4831b63d9ebfac6b6fb2;m=2f3c47b;t=57b98797ff589;x=4ed15931e599c3cf",
        "__REALTIME_TIMESTAMP" : "1543269687227785",
        "__MONOTONIC_TIMESTAMP" : "49529979",
        "_BOOT_ID" : "233a251b2d3d4831b63d9ebfac6b6fb2",
        "PRIORITY" : "6",
        "_UID" : "0",
        "_GID" : "0",
        "_MACHINE_ID" : "81c211dd7e6f428995dec2e9d999c878",
        "_HOSTNAME" : "localhost.localdomain",
        "SYSLOG_FACILITY" : "3",
        "SYSLOG_IDENTIFIER" : "systemd",
        "CODE_FILE" : "src/core/job.c",
        "CODE_LINE" : "776",
        "CODE_FUNCTION" : "job_log_status_message",
        "MESSAGE_ID" : "39f53479d3a045ac8e11786248231fbf",
        "RESULT" : "done",
        "_TRANSPORT" : "journal",
        "_PID" : "1",
        "_COMM" : "systemd",
        "_EXE" : "/usr/lib/systemd/systemd",
        "_CAP_EFFECTIVE" : "1fffffffff",
        "_SYSTEMD_CGROUP" : "/",
        "_CMDLINE" : "/usr/lib/systemd/systemd --switched-root --system --deserialize 22",
        "UNIT" : "postfix.service",
        "MESSAGE" : "Started Postfix Mail Transport Agent.",
        "_SOURCE_REALTIME_TIMESTAMP" : "1543269687226838"
}
[root@localhost ~]# 
</code><code>
[root@localhost ~]# journalctl -u postfix -o short-monotonic 
-- Logs begin at Mon 2018-11-26 13:22:30 CET, end at Mon 2018-11-26 23:11:11 CET. --
[   42.829163] localhost.localdomain systemd[1]: Starting Postfix Mail Transport Agent...
[   47.332654] localhost.localdomain postfix/postfix-script[1464]: starting the Postfix mail system
[   47.727793] localhost.localdomain postfix/master[1466]: daemon started -- version 2.10.1, configuration /etc/postfix
[   47.731300] localhost.localdomain systemd[1]: Started Postfix Mail Transport Agent.
[14548.219364] localhost.localdomain systemd[1]: Stopping Postfix Mail Transport Agent...
[14548.477386] localhost.localdomain systemd[1]: Stopped Postfix Mail Transport Agent.
-- Reboot --
[   43.798957] localhost.localdomain systemd[1]: Starting Postfix Mail Transport Agent...
[   49.245069] localhost.localdomain postfix/postfix-script[1464]: starting the Postfix mail system
[   49.527571] localhost.localdomain postfix/master[1466]: daemon started -- version 2.10.1, configuration /etc/postfix
[   49.529979] localhost.localdomain systemd[1]: Started Postfix Mail Transport Agent.
[root@localhost ~]# 

</code>
  - Modifica della configurazione\\ Disabilitare lo storage per i log, e verificare che rsyslogd non logga piu' <code>
[root@localhost ~]# logger -p user.info "logger message prio info"
[root@localhost ~]# tail -n 2 /var/log/messages
Nov 26 23:13:11 localhost nm-dispatcher: req:1 'dhcp4-change' [enp0s8]: start running ordered scripts...
Nov 26 23:14:20 localhost root: logger message prio info
[root@localhost ~]# 
</code><code>
[root@localhost ~]# vi /etc/systemd/journald.conf 
[root@localhost ~]# grep ^Storage /etc/systemd/journald.conf 
Storage=none
[root@localhost ~]# systemctl restart systemd-journald
</code><code>
[root@localhost ~]# journalctl -n 5 --no-pager
-- Logs begin at Mon 2018-11-26 13:22:30 CET, end at Mon 2018-11-26 23:15:53 CET. --
Nov 26 23:15:50 localhost.localdomain systemd[1]: Started Cleanup of Temporary Directories.
Nov 26 23:15:50 localhost.localdomain systemd[1]: [/usr/lib/systemd/system/firstboot-graphical.service:14] Support for option SysVStartPriority= has been removed and it is ignored
Nov 26 23:15:53 localhost.localdomain polkitd[782]: Registered Authentication Agent for unix-process:2280:91607 (system bus name :1.37 [/usr/bin/pkttyagent --notify-fd 5 --fallback], object path /org/freedesktop/PolicyKit1/AuthenticationAgent, locale en_US.UTF-8)
Nov 26 23:15:53 localhost.localdomain systemd[1]: Stopping Flush Journal to Persistent Storage...
Nov 26 23:15:53 localhost.localdomain systemd-journal[458]: Journal stopped
[root@localhost ~]# logger -p user.err "logger message prio err again"
[root@localhost ~]# journalctl -n 5 --no-pager
-- Logs begin at Mon 2018-11-26 13:22:30 CET, end at Mon 2018-11-26 23:15:53 CET. --
Nov 26 23:15:50 localhost.localdomain systemd[1]: Started Cleanup of Temporary Directories.
Nov 26 23:15:50 localhost.localdomain systemd[1]: [/usr/lib/systemd/system/firstboot-graphical.service:14] Support for option SysVStartPriority= has been removed and it is ignored
Nov 26 23:15:53 localhost.localdomain polkitd[782]: Registered Authentication Agent for unix-process:2280:91607 (system bus name :1.37 [/usr/bin/pkttyagent --notify-fd 5 --fallback], object path /org/freedesktop/PolicyKit1/AuthenticationAgent, locale en_US.UTF-8)
Nov 26 23:15:53 localhost.localdomain systemd[1]: Stopping Flush Journal to Persistent Storage...
Nov 26 23:15:53 localhost.localdomain systemd-journal[458]: Journal stopped
[root@localhost ~]# grep "prio err again" /var/log/messages
[root@localhost ~]# 
</code><code>
[root@localhost ~]# vi /etc/systemd/journald.conf 
[root@localhost ~]# grep ^Storage /etc/systemd/journald.conf 
[root@localhost ~]# systemctl restart systemd-journald
[root@localhost ~]# logger -p user.err "logger message prio err again again"
[root@localhost ~]# journalctl -n 5 --no-pager
-- Logs begin at Mon 2018-11-26 13:22:30 CET, end at Mon 2018-11-26 23:19:09 CET. --
Nov 26 23:19:05 localhost.localdomain systemd-journal[2341]: Journal started
Nov 26 23:19:05 localhost.localdomain polkitd[782]: Unregistered Authentication Agent for unix-process:2334:110793 (system bus name :1.38, object path /org/freedesktop/PolicyKit1/AuthenticationAgent, locale en_US.UTF-8) (disconnected from bus)
Nov 26 23:19:05 localhost.localdomain systemd[1]: Starting Flush Journal to Persistent Storage...
Nov 26 23:19:05 localhost.localdomain systemd[1]: Started Flush Journal to Persistent Storage.
Nov 26 23:19:09 localhost.localdomain root[2352]: logger message prio err again again
[root@localhost ~]# grep "prio err again" /var/log/messages
Nov 26 23:19:09 localhost root: logger message prio err again again
[root@localhost ~]# 

</code>

==== Parte 6: systemd utilities =====

  - Visualizzare e modificare i diversi valori di host name tramite hostnamectl <code>
[root@localhost ~]# hostnamectl --static
localhost.localdomain
[root@localhost ~]# cat /etc/hostname 
localhost.localdomain
[root@localhost ~]# hostnamectl --transient
localhost.localdomain
[root@localhost ~]# hostnamectl --pretty

[root@localhost ~]# cat /etc/machine.info
cat: /etc/machine.info: No such file or directory
[root@localhost ~]# 
</code><code>
[root@localhost ~]# hostnamectl --static set-hostname statichostname
[root@localhost ~]# hostnamectl --transient set-hostname transienthostname
[root@localhost ~]# hostnamectl --pretty set-hostname prettyhostname
[root@localhost ~]# 
[root@localhost ~]# hostnamectl --static
statichostname
[root@localhost ~]# cat /etc/hostname 
statichostname
[root@localhost ~]# hostnamectl --transient
transienthostname
[root@localhost ~]# hostnamectl --pretty
prettyhostname
[root@localhost ~]# cat /etc/machine-info 
PRETTY_HOSTNAME=prettyhostname
[root@localhost ~]# 

</code>
  - Modificare la timezone del sistema (verificare che i journal log cambiano la data) <code>
[root@localhost ~]# timedatectl 
      Local time: Mon 2018-11-26 23:26:23 CET
  Universal time: Mon 2018-11-26 22:26:23 UTC
        RTC time: Mon 2018-11-26 16:38:43
       Time zone: Europe/Rome (CET, +0100)
     NTP enabled: yes
NTP synchronized: yes
 RTC in local TZ: no
      DST active: no
 Last DST change: DST ended at
                  Sun 2018-10-28 02:59:59 CEST
                  Sun 2018-10-28 02:00:00 CET
 Next DST change: DST begins (the clock jumps one hour forward) at
                  Sun 2019-03-31 01:59:59 CET
                  Sun 2019-03-31 03:00:00 CEST
[root@localhost ~]# timedatectl list-timezones | grep -i new
America/New_York
America/North_Dakota/New_Salem
[root@localhost ~]# timedatectl set-timezone America/New_York
[root@localhost ~]# date
Mon Nov 26 17:27:05 EST 2018
[root@localhost ~]# journalctl -n 4
-- Logs begin at Mon 2018-11-26 07:22:30 EST, end at Mon 2018-11-26 17:26:59 EST. --
Nov 26 17:26:59 statichostname dbus[757]: [system] Successfully activated service 'org.freedesktop.timedate1'
Nov 26 17:26:59 statichostname systemd[1]: Started Time & Date Service.
Nov 26 17:26:59 statichostname systemd-timedated[2564]: Changed time zone to 'America/New_York'.
Nov 26 17:26:59 statichostname polkitd[782]: Unregistered Authentication Agent for unix-process:2559:158162 (system bus name :1.64, object path /org/freedesktop/Policy
[root@localhost ~]# 
</code>
  - Modificare l'ora del sistema (si deve disabilitare NTP: verificare che chronyd viene fermato) <code>
[root@localhost ~]# date
Mon Nov 26 17:28:29 EST 2018
[root@localhost ~]# timedatectl set-time "17:35"
Failed to set time: Automatic time synchronization is enabled
[root@localhost ~]# systemctl status chronyd 
● chronyd.service - NTP client/server
   Loaded: loaded (/usr/lib/systemd/system/chronyd.service; enabled; vendor preset: enabled)
   Active: active (running) since Mon 2018-11-26 11:13:25 EST; 6h ago
...
[root@localhost ~]# timedatectl set-ntp false
[root@localhost ~]# systemctl status chronyd 
● chronyd.service - NTP client/server
   Loaded: loaded (/usr/lib/systemd/system/chronyd.service; disabled; vendor preset: enabled)
   Active: inactive (dead)
...
Nov 26 17:06:50 localhost.localdomain chronyd[814]: Source 85.10.240.253 replaced with 185.19.184.35
Nov 26 17:29:29 statichostname systemd[1]: Stopping NTP client/server...
Nov 26 17:29:29 statichostname systemd[1]: Stopped NTP client/server.
Hint: Some lines were ellipsized, use -l to show in full.
[root@localhost ~]# timedatectl set-time "17:00"
[root@localhost ~]# date
Mon Nov 26 17:00:02 EST 2018
[root@localhost ~]# timedatectl set-ntp true
[root@localhost ~]# systemctl status chronyd 
● chronyd.service - NTP client/server
   Loaded: loaded (/usr/lib/systemd/system/chronyd.service; enabled; vendor preset: enabled)
   Active: active (running) since Mon 2018-11-26 17:00:09 EST; 4s ago
...
[root@localhost ~]# timedatectl set-timezone Europe/Rome 
[root@localhost ~]# date
Mon Nov 26 23:00:32 CET 2018
[root@localhost ~]# 

</code>