systemd service freezes in activating (start-post) status – mysqld or other services

We’ve experienced this with the MySQL server under CentOS 7, but you can have this state with other services!
After updating our MySQL we tried to start it up, but the service got this strange state after “systemctl start” returned:

[root@mysql2 ~]# systemctl start mysqld
Job for mysqld.service failed because a timeout was exceeded. See "systemctl status mysqld.service" and "journalctl -xe" for details.

The timeout is big it’s something like 5 to 10 minutes and so it is typical (do not do it!) to type “ctrl+c” and you end up without this message and a strange state of the mysql:

[root@mysql2 ~]# systemctl status mysqld
● mysqld.service - MySQL Community Server
   Loaded: loaded (/usr/lib/systemd/system/mysqld.service; enabled; vendor preset: disabled)
   Active: activating (start-post) since Fri 2018-11-09 09:00:55 UTC; 6min ago
  Process: 8333 ExecStart=/usr/bin/mysqld_safe --basedir=/usr (code=exited, status=0/SUCCESS)
  Process: 8321 ExecStartPre=/usr/bin/mysql-systemd-start pre (code=exited, status=0/SUCCESS)
 Main PID: 8333 (code=exited, status=0/SUCCESS);         : 8334 (mysql-systemd-s)
   CGroup: /user.slice/user-0.slice/session-2395.scope/system.slice/mysqld.service
           └─control
             ├─ 8334 /bin/bash /usr/bin/mysql-systemd-start post
             └─10152 sleep 1

Nov 09 09:00:55 mysql2.mytv.bg systemd[1]: Starting MySQL Community Server...
Nov 09 09:00:56 mysql2.mytv.bg mysqld_safe[8333]: 181109 09:00:56 mysqld_safe Logging to '/var/log/mysqld.log'.
Nov 09 09:00:56 mysql2.mytv.bg mysqld_safe[8333]: 181109 09:00:56 mysqld_safe Starting mysqld daemon with databases from /var/lib/mysql

Meanwhile with “pstree”:

[root@mysql2 ~]# pstree
systemd─┬─agetty
        ├─crond
        ├─dbus-daemon
        ├─mysql-systemd-s───sleep
        ├─rsyslogd───2*[{rsyslogd}]
        ├─sshd─┬─sshd───bash───systemctl─┬─systemctl
        │      │                         └─systemd-tty-ask
        │      └─sshd───bash───pstree
        ├─systemd-journal
        └─systemd-logind

So as you can see no mysqld process! Apparently systemctl had tried to start MySQL server process and it failed.
So the first thing to do was to check the MySQL logs. In our case it was a obsolete option in my.cnf:

2018-11-09 09:10:57 11384 [ERROR] /usr/sbin/mysqld: unknown variable 'default-character-set=utf8'
2018-11-09 09:10:57 11384 [ERROR] Aborting

The interesting part is that

the service got “Active: activating (start-post)” and when you fix the problem you cannot “systemctl start mysqld” it just start to wait for the current timeout.

In fact this state means “I’m trying to start the service…” and it is in an endless loop to start the service and if you the service has a big start timeout like 5-10 minutes you must wait for the next iteration of the loop to start the service successfully (if you fixed the problem!). And if you want not to wait you must execute first stop to the service and then start – you’ll not wait for any timeout and you can check immediately if the service was started successfully:

[root@mysql2 ~]# systemctl status mysqld
● mysqld.service - MySQL Community Server
   Loaded: loaded (/usr/lib/systemd/system/mysqld.service; enabled; vendor preset: disabled)
   Active: activating (start-post) since Fri 2018-11-09 09:20:56 UTC; 2min 50s ago
  Process: 13208 ExecStart=/usr/bin/mysqld_safe --basedir=/usr (code=exited, status=0/SUCCESS)
  Process: 13196 ExecStartPre=/usr/bin/mysql-systemd-start pre (code=exited, status=0/SUCCESS)
 Main PID: 13208 (code=exited, status=0/SUCCESS);         : 13209 (mysql-systemd-s)
   CGroup: /user.slice/user-0.slice/session-2395.scope/system.slice/mysqld.service
           └─control
             ├─13209 /bin/bash /usr/bin/mysql-systemd-start post
             └─14357 sleep 1

Nov 09 09:20:56 mysql2.mytv.bg systemd[1]: Starting MySQL Community Server...
Nov 09 09:20:56 mysql2.mytv.bg mysqld_safe[13208]: 181109 09:20:56 mysqld_safe Logging to '/var/log/mysqld.log'.
Nov 09 09:20:56 mysql2.mytv.bg mysqld_safe[13208]: 181109 09:20:56 mysqld_safe Starting mysqld daemon with databases from /var/lib/mysql
[root@mysql2 ~]# systemctl start mysqld
Job for mysqld.service failed because a timeout was exceeded. See "systemctl status mysqld.service" and "journalctl -xe" for details.
[root@mysql2 ~]# systemctl status mysqld
● mysqld.service - MySQL Community Server
   Loaded: loaded (/usr/lib/systemd/system/mysqld.service; enabled; vendor preset: disabled)
   Active: active (running) since Fri 2018-11-09 09:30:59 UTC; 2s ago
  Process: 15656 ExecStartPost=/usr/bin/mysql-systemd-start post (code=exited, status=0/SUCCESS)
  Process: 15643 ExecStartPre=/usr/bin/mysql-systemd-start pre (code=exited, status=0/SUCCESS)
 Main PID: 15655 (mysqld_safe)
   CGroup: /user.slice/user-0.slice/session-2395.scope/system.slice/mysqld.service
           ├─15655 /bin/sh /usr/bin/mysqld_safe --basedir=/usr
           └─16243 /usr/sbin/mysqld --basedir=/usr --datadir=/var/lib/mysql --plugin-dir=/usr/lib64/mysql/plugin --log-error=/var/log/mysqld.log --open-files-limit=10000...

Nov 09 09:30:56 mysql2.mytv.bg systemd[1]: Starting MySQL Community Server...
Nov 09 09:30:57 mysql2.mytv.bg mysqld_safe[15655]: 181109 09:30:57 mysqld_safe Logging to '/var/log/mysqld.log'.
Nov 09 09:30:57 mysql2.mytv.bg mysqld_safe[15655]: 181109 09:30:57 mysqld_safe Starting mysqld daemon with databases from /var/lib/mysql
Nov 09 09:30:59 mysql2.mytv.bg systemd[1]: Started MySQL Community Server.

As you can see we even received error again that the service cannot be started and immediately after that the service status is in normal “active (running)” state! And we waited for around 10 minutes! You can see the times in the logs above.
So to summarize it up:

If you have a service in “activating (start-post)” the service cannot be started because of an error, check and fix the problem and then issue “stop and start”:

[root@mysql2 ~]# systemctl start mysqld
Job for mysqld.service failed because a timeout was exceeded. See "systemctl status mysqld.service" and "journalctl -xe" for details.
[root@mysql2 ~]# systemctl status mysqld
● mysqld.service - MySQL Community Server
   Loaded: loaded (/usr/lib/systemd/system/mysqld.service; enabled; vendor preset: disabled)
   Active: activating (start-post) since Fri 2018-11-09 10:05:20 UTC; 2min 17s ago
  Process: 23601 ExecStart=/usr/bin/mysqld_safe --basedir=/usr (code=exited, status=0/SUCCESS)
  Process: 23589 ExecStartPre=/usr/bin/mysql-systemd-start pre (code=exited, status=0/SUCCESS)
 Main PID: 23601 (code=exited, status=0/SUCCESS);         : 23602 (mysql-systemd-s)
   CGroup: /user.slice/user-0.slice/session-2395.scope/system.slice/mysqld.service
           └─control
             ├─23602 /bin/bash /usr/bin/mysql-systemd-start post
             └─24646 sleep 1

Nov 09 10:05:20 mysql2.mytv.bg systemd[1]: Starting MySQL Community Server...
Nov 09 10:05:21 mysql2.mytv.bg mysqld_safe[23601]: 181109 10:05:21 mysqld_safe Logging to '/var/log/mysqld.log'.
Nov 09 10:05:21 mysql2.mytv.bg mysqld_safe[23601]: 181109 10:05:21 mysqld_safe Starting mysqld daemon with databases from /var/lib/mysql
[root@mysql2 ~]# systemctl stop mysqld
[root@mysql2 ~]# systemctl status mysqld
● mysqld.service - MySQL Community Server
   Loaded: loaded (/usr/lib/systemd/system/mysqld.service; enabled; vendor preset: disabled)
   Active: inactive (dead) since Fri 2018-11-09 10:07:52 UTC; 4s ago
  Process: 23602 ExecStartPost=/usr/bin/mysql-systemd-start post (code=killed, signal=TERM)
  Process: 23601 ExecStart=/usr/bin/mysqld_safe --basedir=/usr (code=exited, status=0/SUCCESS)
  Process: 23589 ExecStartPre=/usr/bin/mysql-systemd-start pre (code=exited, status=0/SUCCESS)
 Main PID: 23601 (code=exited, status=0/SUCCESS)

Nov 09 10:05:20 mysql2.mytv.bg systemd[1]: Starting MySQL Community Server...
Nov 09 10:05:21 mysql2.mytv.bg mysqld_safe[23601]: 181109 10:05:21 mysqld_safe Logging to '/var/log/mysqld.log'.
Nov 09 10:05:21 mysql2.mytv.bg mysqld_safe[23601]: 181109 10:05:21 mysqld_safe Starting mysqld daemon with databases from /var/lib/mysql
Nov 09 10:07:52 mysql2.mytv.bg systemd[1]: Stopped MySQL Community Server.
[root@mysql2 ~]# systemctl start mysqld
[root@mysql2 ~]# systemctl status mysqld
● mysqld.service - MySQL Community Server
   Loaded: loaded (/usr/lib/systemd/system/mysqld.service; enabled; vendor preset: disabled)
   Active: active (running) since Fri 2018-11-09 10:08:06 UTC; 3s ago
  Process: 24711 ExecStartPost=/usr/bin/mysql-systemd-start post (code=exited, status=0/SUCCESS)
  Process: 24698 ExecStartPre=/usr/bin/mysql-systemd-start pre (code=exited, status=0/SUCCESS)
 Main PID: 24710 (mysqld_safe)
   CGroup: /user.slice/user-0.slice/session-2395.scope/system.slice/mysqld.service
           ├─24710 /bin/sh /usr/bin/mysqld_safe --basedir=/usr
           └─25298 /usr/sbin/mysqld --basedir=/usr --datadir=/var/lib/mysql --plugin-dir=/usr/lib64/mysql/plugin --log-error=/var/log/mysqld.log --open-files-limit=10000...

Nov 09 10:08:04 mysql2.mytv.bg systemd[1]: Starting MySQL Community Server...
Nov 09 10:08:04 mysql2.mytv.bg mysqld_safe[24710]: 181109 10:08:04 mysqld_safe Logging to '/var/log/mysqld.log'.
Nov 09 10:08:04 mysql2.mytv.bg mysqld_safe[24710]: 181109 10:08:04 mysqld_safe Starting mysqld daemon with databases from /var/lib/mysql
Nov 09 10:08:06 mysql2.mytv.bg systemd[1]: Started MySQL Community Server.

Clear or delete systemd logs

Systemd linux distros use Journald service to collect and store logs in the system. Here are a couple of tips if you have problems with the space they occupy. It is good that all systemd linux distros support it – CentOS 7, Ubuntu 16+, Fedora, OpenSuse and so on.

TIP 1) Remove the old archive logs older than 10 days with

Time based removal of old logs. It will remove the old files. This command won’t change the configuration, so it just has a temporary effect.

journalctl --vacuum-time=10d

TIP 2) Remove the old archive logs greater than 1G

Size based removal of old logs. It will reduce the size of the logs to this specified size. This command won’t change the configuration, so it just has a temporary effect.

journalctl --vacuum-size=1024M

TIP 3) Show disk usage

[root@srv ~]# journalctl --disk-usage
Archived and active journals take up 785.5M on disk.

TIP 4) Show all logs and information for them

Where are the log files, the size they occupy, the time period of the entries in them and more:

[root@srv0 ~]# journalctl --header
File Path: /run/log/journal/bb5aa69bfa2b483386443ede7a92a45a/system.journal
File ID: 7deaff4610a94c82aab85386597e825b
Machine ID: bb5aa69bfa2b483386443ede7a92a45a
Boot ID: e89507fa3f814b8a96f9d70914c120b0
Sequential Number ID: 541a59d9a68342d3980d86e565a48c7d
State: ONLINE
Compatible Flags:
Incompatible Flags: COMPRESSED-XZ
Header size: 240
Arena size: 102956816
Data Hash Table Size: 178744
Field Hash Table Size: 333
Rotate Suggested: no
Head Sequential Number: 1239405
Tail Sequential Number: 1341511
Head Realtime Timestamp: mon 2018-06-25 10:09:09 UTC
Tail Realtime Timestamp: tue 2018-06-28 00:07:10 UTC
Tail Monotonic Timestamp: 1month 2d 21h 6min 47.287s
Objects: 258136
Entry Objects: 102107
Data Objects: 129585
Data Hash Table Fill: 72.5%
Field Objects: 36
Field Hash Table Fill: 10.8%
Tag Objects: 0
Entry Array Objects: 26406
Disk usage: 98.1M

File Path: /run/log/journal/bb5aa69bfa2b483386443ede7a92a45a/system@541a59d9a68342d3980d86e565a48c7d-000000000011512d-00056f3f3ff56172.journal
File ID: a8e1f042bc144df78f37005b0b555a82
Machine ID: bb5aa69bfa2b483386443ede7a92a45a
Boot ID: e89507fa3f814b8a96f9d70914c120b0
Sequential Number ID: 541a59d9a68342d3980d86e565a48c7d
State: ARCHIVED
Compatible Flags:
Incompatible Flags: COMPRESSED-XZ
Header size: 240
Arena size: 102956816
Data Hash Table Size: 178744
Field Hash Table Size: 333
Rotate Suggested: no
Head Sequential Number: 1134893
Tail Sequential Number: 1239404
Head Realtime Timestamp: fri 2018-06-22 18:32:10 UTC
Tail Realtime Timestamp: mon 2018-06-25 10:09:09 UTC
Tail Monotonic Timestamp: 1month 7h 8min 45.991s
Objects: 263445
Entry Objects: 104512
Data Objects: 131953
Data Hash Table Fill: 73.8%
Field Objects: 34
Field Hash Table Fill: 10.2%
Tag Objects: 0
Entry Array Objects: 26944
Disk usage: 98.1M

File Path: /run/log/journal/bb5aa69bfa2b483386443ede7a92a45a/system@541a59d9a68342d3980d86e565a48c7d-00000000000fc083-00056f0d6ef70320.journal
File ID: 007272b1f181487d83116bee96c40c30
Machine ID: bb5aa69bfa2b483386443ede7a92a45a
Boot ID: e89507fa3f814b8a96f9d70914c120b0
Sequential Number ID: 541a59d9a68342d3980d86e565a48c7d
State: ARCHIVED
Compatible Flags:
Incompatible Flags: COMPRESSED-XZ
Header size: 240
Arena size: 102956816
Data Hash Table Size: 178744
Field Hash Table Size: 333
Rotate Suggested: no
Head Sequential Number: 1032323
Tail Sequential Number: 1134892
Head Realtime Timestamp: wed 2018-06-20 07:06:10 UTC
Tail Realtime Timestamp: fri 2018-06-22 18:32:10 UTC
Tail Monotonic Timestamp: 4w 2h 1min 46.980s
Objects: 263998
Entry Objects: 102570
Data Objects: 133456
Data Hash Table Fill: 74.7%
Field Objects: 37
Field Hash Table Fill: 11.1%
Tag Objects: 0
Entry Array Objects: 27933
Disk usage: 98.1M

File Path: /run/log/journal/bb5aa69bfa2b483386443ede7a92a45a/system@541a59d9a68342d3980d86e565a48c7d-00000000000e3f67-00056ee09376d287.journal
File ID: 4c268268a6e34d6297c7ae9ca01fc31b
Machine ID: bb5aa69bfa2b483386443ede7a92a45a
Boot ID: e89507fa3f814b8a96f9d70914c120b0
Sequential Number ID: 541a59d9a68342d3980d86e565a48c7d
State: ARCHIVED
Compatible Flags:
Incompatible Flags: COMPRESSED-XZ
Header size: 240
Arena size: 102956816
Data Hash Table Size: 178744
Field Hash Table Size: 333
Rotate Suggested: yes
Head Sequential Number: 933735
Tail Sequential Number: 1032322
Head Realtime Timestamp: mon 2018-06-18 01:35:09 UTC
Tail Realtime Timestamp: wed 2018-06-20 07:06:10 UTC
Tail Monotonic Timestamp: 3w 4d 14h 35min 47.248s
Objects: 261498
Entry Objects: 98588
Data Objects: 134059
Data Hash Table Fill: 75.0%
Field Objects: 40
Field Hash Table Fill: 12.0%
Tag Objects: 0
Entry Array Objects: 28809
Disk usage: 98.1M

File Path: /run/log/journal/bb5aa69bfa2b483386443ede7a92a45a/system@541a59d9a68342d3980d86e565a48c7d-00000000000cbf3b-00056eb3ea255b2a.journal
File ID: 7019a721bebe4e00b76410a6e7052c6d
Machine ID: bb5aa69bfa2b483386443ede7a92a45a
Boot ID: e89507fa3f814b8a96f9d70914c120b0
Sequential Number ID: 541a59d9a68342d3980d86e565a48c7d
State: ARCHIVED
Compatible Flags:
Incompatible Flags: COMPRESSED-XZ
Header size: 240
Arena size: 102956816
Data Hash Table Size: 178744
Field Hash Table Size: 333
Rotate Suggested: yes
Head Sequential Number: 835387
Tail Sequential Number: 933734
Head Realtime Timestamp: fri 2018-06-15 20:18:10 UTC
Tail Realtime Timestamp: mon 2018-06-18 01:35:09 UTC
Tail Monotonic Timestamp: 3w 2d 9h 4min 45.972s
Objects: 260794
Entry Objects: 98348
Data Objects: 134060
Data Hash Table Fill: 75.0%
Field Objects: 33
Field Hash Table Fill: 9.9%
Tag Objects: 0
Entry Array Objects: 28351
Disk usage: 98.1M

File Path: /run/log/journal/bb5aa69bfa2b483386443ede7a92a45a/system@541a59d9a68342d3980d86e565a48c7d-00000000000b2fac-00056e827d3375dd.journal
File ID: 61c16e8acc364d97b8c0c7cc2afcb6ec
Machine ID: bb5aa69bfa2b483386443ede7a92a45a
Boot ID: e89507fa3f814b8a96f9d70914c120b0
Sequential Number ID: 541a59d9a68342d3980d86e565a48c7d
State: ARCHIVED
Compatible Flags:
Incompatible Flags: COMPRESSED-XZ
Header size: 240
Arena size: 102956816
Data Hash Table Size: 178744
Field Hash Table Size: 333
Rotate Suggested: no
Head Sequential Number: 733100
Tail Sequential Number: 835386
Head Realtime Timestamp: wed 2018-06-13 09:20:08 UTC
Tail Realtime Timestamp: fri 2018-06-15 20:18:10 UTC
Tail Monotonic Timestamp: 3w 3h 47min 46.827s
Objects: 264298
Entry Objects: 102287
Data Objects: 134043
Data Hash Table Fill: 75.0%
Field Objects: 33
Field Hash Table Fill: 9.9%
Tag Objects: 0
Entry Array Objects: 27933
Disk usage: 98.1M

File Path: /run/log/journal/bb5aa69bfa2b483386443ede7a92a45a/system@541a59d9a68342d3980d86e565a48c7d-000000000009966a-00056e4cbbb6ebfc.journal
File ID: c90df7bdc4654ab7a4ac955c74a779a3
Machine ID: bb5aa69bfa2b483386443ede7a92a45a
Boot ID: e89507fa3f814b8a96f9d70914c120b0
Sequential Number ID: 541a59d9a68342d3980d86e565a48c7d
State: ARCHIVED
Compatible Flags:
Incompatible Flags: COMPRESSED-XZ
Header size: 240
Arena size: 102956816
Data Hash Table Size: 178744
Field Hash Table Size: 333
Rotate Suggested: no
Head Sequential Number: 628330
Tail Sequential Number: 733099
Head Realtime Timestamp: sun 2018-06-10 17:12:09 UTC
Tail Realtime Timestamp: wed 2018-06-13 09:19:10 UTC
Tail Monotonic Timestamp: 2w 4d 16h 48min 46.993s
Objects: 263295
Entry Objects: 104770
Data Objects: 131816
Data Hash Table Fill: 73.7%
Field Objects: 37
Field Hash Table Fill: 11.1%
Tag Objects: 0
Entry Array Objects: 26670
Disk usage: 98.1M

File Path: /run/log/journal/bb5aa69bfa2b483386443ede7a92a45a/system@541a59d9a68342d3980d86e565a48c7d-000000000007fd20-00056e16f3135f30.journal
File ID: 32915d651dd84728b9e4a33a97b480cf
Machine ID: bb5aa69bfa2b483386443ede7a92a45a
Boot ID: e89507fa3f814b8a96f9d70914c120b0
Sequential Number ID: 541a59d9a68342d3980d86e565a48c7d
State: ARCHIVED
Compatible Flags:
Incompatible Flags: COMPRESSED-XZ
Header size: 240
Arena size: 102956816
Data Hash Table Size: 178744
Field Hash Table Size: 333
Rotate Suggested: no
Head Sequential Number: 523552
Tail Sequential Number: 628329
Head Realtime Timestamp: fri 2018-06-08 01:02:10 UTC
Tail Realtime Timestamp: sun 2018-06-10 17:12:09 UTC
Tail Monotonic Timestamp: 2w 2d 41min 46.200s
Objects: 263287
Entry Objects: 104778
Data Objects: 131696
Data Hash Table Fill: 73.7%
Field Objects: 36
Field Hash Table Fill: 10.8%
Tag Objects: 0
Entry Array Objects: 26775
Disk usage: 98.1M
[root@srv0 ~]#

* Deleting logs

[root@srv0 ~]# journalctl --vacuum-size=128M
Deleted archived journal /var/log/journal/9be717e698354ec481abb641cf4085c3/system@79d0440cc1174c2db132b707a0567bcb-0000000000a33241-000570199db5be3c.journal (8.0M).
Deleted archived journal /var/log/journal/9be717e698354ec481abb641cf4085c3/system@79d0440cc1174c2db132b707a0567bcb-0000000000a34463-0005701a0b24d0fc.journal (8.0M).
Deleted archived journal /var/log/journal/9be717e698354ec481abb641cf4085c3/system@79d0440cc1174c2db132b707a0567bcb-0000000000a3568c-0005701a79e388c7.journal (8.0M).
Deleted archived journal /var/log/journal/9be717e698354ec481abb641cf4085c3/system@79d0440cc1174c2db132b707a0567bcb-0000000000a36899-0005701ae529f439.journal (8.0M).
Deleted archived journal /var/log/journal/9be717e698354ec481abb641cf4085c3/system@79d0440cc1174c2db132b707a0567bcb-0000000000a37ac8-0005701b50781f62.journal (8.0M).
Deleted archived journal /var/log/journal/9be717e698354ec481abb641cf4085c3/system@79d0440cc1174c2db132b707a0567bcb-0000000000a38cde-0005701bbd3b60c3.journal (8.0M).
Deleted archived journal /var/log/journal/9be717e698354ec481abb641cf4085c3/system@79d0440cc1174c2db132b707a0567bcb-0000000000a39ef6-0005701c28dcf40e.journal (8.0M).
Deleted archived journal /var/log/journal/9be717e698354ec481abb641cf4085c3/system@79d0440cc1174c2db132b707a0567bcb-0000000000a3b0f1-0005701c9416ee94.journal (8.0M).
Deleted archived journal /var/log/journal/9be717e698354ec481abb641cf4085c3/system@79d0440cc1174c2db132b707a0567bcb-0000000000a3c309-0005701cffe19015.journal (8.0M).
Deleted archived journal /var/log/journal/9be717e698354ec481abb641cf4085c3/system@79d0440cc1174c2db132b707a0567bcb-0000000000a3d521-0005701d6c79b9cb.journal (8.0M).
Deleted archived journal /var/log/journal/9be717e698354ec481abb641cf4085c3/system@79d0440cc1174c2db132b707a0567bcb-0000000000a3e748-0005701dd7c60e79.journal (8.0M).
Deleted archived journal /var/log/journal/9be717e698354ec481abb641cf4085c3/system@79d0440cc1174c2db132b707a0567bcb-0000000000a3f92d-0005701e48413eb8.journal (8.0M).
Deleted archived journal /var/log/journal/9be717e698354ec481abb641cf4085c3/system@79d0440cc1174c2db132b707a0567bcb-0000000000a40b0a-0005701ec83a0c74.journal (8.0M).
Deleted archived journal /var/log/journal/9be717e698354ec481abb641cf4085c3/system@79d0440cc1174c2db132b707a0567bcb-0000000000a41ce2-0005701f3fdcadc6.journal (8.0M).
Deleted archived journal /var/log/journal/9be717e698354ec481abb641cf4085c3/system@79d0440cc1174c2db132b707a0567bcb-0000000000a42f04-0005701fabfefbca.journal (8.0M).
Deleted archived journal /var/log/journal/9be717e698354ec481abb641cf4085c3/system@79d0440cc1174c2db132b707a0567bcb-0000000000a4410e-000570201757a256.journal (120.0M).
Deleted archived journal /var/log/journal/9be717e698354ec481abb641cf4085c3/system@79d0440cc1174c2db132b707a0567bcb-0000000000a60a8f-0005702ac025bb0c.journal (120.0M).
Deleted archived journal /var/log/journal/9be717e698354ec481abb641cf4085c3/system@79d0440cc1174c2db132b707a0567bcb-0000000000a7d254-000570359f2bd7eb.journal (120.0M).
Deleted archived journal /var/log/journal/9be717e698354ec481abb641cf4085c3/system@79d0440cc1174c2db132b707a0567bcb-0000000000a99a34-000570405b5e812e.journal (120.0M).
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systemd can be used to run your application as a daemon

A nice feature of systemd is the scripts could be daemonized without any modifications of the scripts like standard stdin, stdout, stderr to be redirected to null (and even in some languages is not that simple!).
So if you want to run your ordinary script as daemon under a systemd linux distro, create a systemd service file in

/etc/systemd/system/myscript.service

Replace “myscript” with the nme of your script.

[Install]
WantedBy=multi-user.target

[Unit]
Description=<my_script_description>
After=syslog.target
After=network.target

[Service]
Type=simple
User=<run_as_user>
Group=<run_as_group_group>
ExecStart=<your_path_and_script_name_here>

# Give the script some time to startup
TimeoutSec=300
#EnvironmentFile=/etc/<filename>

[Install]
WantedBy=multi-user.target

So change the following according your needs:

  • <my_script_description> – description of your script/program with couple of words
  • <run_as_user> – the user under which will be executed
  • <run_as_group_group> – the group under which will be executed
  • <your_path_and_script_name_here> – the absolute path and filename to the script or program to be executed
  • Uncomment “EnvironmentFile” line if you would like to have different environment file for your script

And then you can run it with

systemctl start myscript

And you can enable it to start at boot

systemctl enable myscript

And also you can see the output of the script on syslog or with

systemctl status myscript

Here is an example of running a python script as a daemon with systemd.
The python script is

/usr/local/bin/mypythonscript.py

and the service name is

/etc/systemd/system/mypythonscript.service

Description=My python script daemon
After=syslog.target
After=network.target

[Service]
Type=simple
User=root
Group=root
ExecStart=/usr/bin/python /usr/local/bin/mypythonscript.py

# Give the script some time to startup
TimeoutSec=300

[Install]
WantedBy=multi-user.target

And you can see handful of information for the state of your script with

systemctl status mypythonscript

The uptime of your script and output if any

* mypythonscript.service
   Loaded: loaded (/etc/systemd/system/mypythonscript.service; disabled; vendor preset: enabled)
   Active: active (running) since Thu 2018-01-04 13:58:34 UTC; 1 months 12 days ago
 Main PID: 29654 (python)
   CGroup: /system.slice/mypythonscript.service
           `-37421 /usr/bin/python /usr/local/bin/mypythonscript.py

Jan 12 10:05:21 srv.local systemd[1]: [/etc/systemd/system/mypythonscript.service:3] Assignment outside of section. Ignoring.
Jan 12 10:05:21 srv.local systemd[1]: [/etc/systemd/system/mypythonscript.service:1] Assignment outside of section. Ignoring.