{"id":10840,"date":"2024-12-14T07:08:13","date_gmt":"2024-12-14T07:08:13","guid":{"rendered":"https:\/\/blog.trustedhosting.in\/?p=10840"},"modified":"2024-12-14T07:08:13","modified_gmt":"2024-12-14T07:08:13","slug":"service-management-on-centos-6","status":"publish","type":"post","link":"https:\/\/www.webystrata.com\/blog\/service-management-on-centos-6\/","title":{"rendered":"Service Management on CentOS 6"},"content":{"rendered":"
\"Service<\/a>
\u00a0<\/figcaption><\/figure>\n

Service Management on CentOS 6<\/h1>\n

On a Linux server<\/a>, a service is an application that is capable of running in the background performing some task or other. This guide will detail the\u00a0SysVinit<\/span><\/code>\u00a0system and how you can manage services with it.<\/p>\n

To keep in the scope of this tutorial as part of a\u00a0Linux basics<\/span>\u00a0series, we\u2019ll only be covering two of the most common services you\u2019ll come across when managing a Linux web server,\u00a0Apache<\/span><\/code>\u00a0and\u00a0MySQL<\/span><\/code><\/p>\n

Our main tool for interacting with services on Linux is fairly straight forward:\u00a0service<\/span><\/code><\/p>\n

The syntax for common tasks is fairly self explanatory and takes the following format:<\/p>\n

\n
\n
service {<\/span>servicename}<\/span> {<\/span>command}<\/span>\r\n<\/pre>\n<\/div>\n<\/div>\n
Below are a few sections on common tasks with some examples.<\/p>\n
As a broad rule, all service management should be carried out as the\u00a0root<\/span><\/code>\u00a0user, so make sure you\u2019re logged into that account or have access to one with\u00a0sudo<\/span><\/code>.<\/p>\n
\n
Starting services<\/h2>\n
The argument to start a service is simply\u00a0start<\/span><\/code>, so using the structure above with the\u00a0httpd<\/span><\/code>\u00a0(Red Hat distributions use this name for Apache) we get the following command:<\/p>\n
\n
\n
service httpd start\r\n<\/pre>\n<\/div>\n<\/div>\n
This will return some content letting you know if the service started successfully or not before dropping you back to your prompt ready to enter more commands:<\/p>\n
\n
\n
[root@94 ~]# <\/span>service httpd start\r\nStarting httpd:                                            [  OK  ]<\/span>\r\n[root@94 ~]#<\/span>\r\n<\/pre>\n<\/div>\n<\/div>\n
If the service failed to start, it may give you information on why it failed to start or it may simply say\u00a0FAILED<\/span><\/code>:<\/p>\n
\n
\n
[ukfastsupport@94 ~]$ <\/span>service httpd start\r\nStarting httpd: (13)Permission denied: make_sock: could not bind to address [::]:80<\/span>\r\n(13)<\/span>Permission denied: make_sock: could not bind to address 0.0.0.0:80<\/span>\r\nno listening sockets available, shutting down<\/span>\r\nUnable to open logs<\/span>\r\n                                                            [FAILED]<\/span>\r\n[ukfastsupport@94 ~]$<\/span>\r\n<\/pre>\n<\/div>\n<\/div>\n
The above example was actually fairly descriptive, letting us know that the user we were using didn\u2019t have necessary permission to start the service, but don\u2019t be surprised if you get little to no information. Such is the joy of Linux. Learning to diagnose why services won\u2019t\/can\u2019t start is beyond the scope of this article but will be covered elsewhere in our documentation in the future.<\/p>\n<\/section>\n
\n
Stopping services<\/h2>\n
Similar to our\u00a0start<\/span><\/code>\u00a0commands above, to stop a services we can just use\u00a0stop<\/span><\/code>\u00a0instead. This time we\u2019ll use MySQL in our example, which has the service name\u00a0mysqld<\/span><\/code>:<\/p>\n
\n
\n
service mysqld stop\r\n<\/pre>\n<\/div>\n<\/div>\n
Again, similar to start, you\u2019ll usually get some amount of feedback to let you know that the service has stopped successfully:<\/p>\n
\n
\n
[root@94 ~]# <\/span>service mysqld start\r\nStarting mysqld:                                           [  OK  ]<\/span>\r\n[root@94 ~]#<\/span>\r\n<\/pre>\n<\/div>\n<\/div>\n<\/section>\n
\n
Restarting services<\/h2>\n
You may have an idea on what command will be needed to restart a service by now. We\u2019ll be needing the\u00a0restart<\/span><\/code>\u00a0argument:<\/p>\n
\n
\n
service httpd restart\r\n<\/pre>\n<\/div>\n<\/div>\n
This will give a combined bit of output as it stops and then starts the service:<\/p>\n
\n
\n
[root@94 ~]# <\/span>service httpd restart\r\nStopping httpd:                                            [  OK  ]<\/span>\r\nStarting httpd:                                            [  OK  ]<\/span>\r\n[root@94 ~]#<\/span>\r\n<\/pre>\n<\/div>\n<\/div>\n<\/section>\n
\n
Checking the status of services<\/h2>\n
It\u2019s sometimes useful to see if a service is running or not, and it may not be immediately apparent, so most (but not all) services implement the\u00a0status<\/span><\/code>\u00a0argument:<\/p>\n
\n
\n
[root@94 ~]# <\/span>service httpd status\r\nhttpd (pid  17462) is running...<\/span>\r\n<\/pre>\n<\/div>\n<\/div>\n
Above, we can see that Apache is up and running quite happily (or at least the service is)<\/p>\n
\n
\n
[root@94 ~]# <\/span>service mysqld status\r\nmysqld is stopped<\/span>\r\n<\/pre>\n<\/div>\n<\/div>\n
Whilst the output varies from service to service, it\u2019s usually fairly clear if the service is running or not.<\/p>\n
You can sometimes even get some information on if the service was stopped cleanly or crashed:<\/p>\n
\n
\n
[root@94 ~]# <\/span>service mysqld status\r\nmysqld dead but subsys locked<\/span>\r\n<\/pre>\n<\/div>\n<\/div>\n<\/section>\n
\n
Starting services on boot<\/h2>\n
One of the most important tasks regarding services is making sure they start automatically, as you don\u2019t want to have to log in after every reboot and start them manually.<\/p>\n
The command for this is\u00a0chkconfig<\/span><\/code>\u00a0on Red Hat\/CentOS systems.<\/p>\n
Usage is fairly simple. To start Red Hat at boot, we\u2019d use the following command:<\/p>\n
\n
\n
chkconfig httpd on\r\n<\/pre>\n<\/div>\n<\/div>\n
To stop MySQL from starting at boot, we could use the inverse:<\/p>\n
\n
\n
chkconfig mysqld off\r\n<\/pre>\n<\/div>\n<\/div>\n
Unlike the\u00a0service<\/span><\/code>\u00a0command above,\u00a0chkconfig<\/span><\/code>\u00a0doesn\u2019t give any output to the command, but we can check what is configured to start on a normal boot using the following, slightly more convoluted, command:<\/p>\n
\n
\n
chkconfig --list|<\/span>grep '3:on'<\/span>\r\n<\/pre>\n<\/div>\n<\/div>\n
This will likely generate quite a lot of output as there are a fair few services that start automatically, but looking down the left hand side you should be able to see that in the following example Red Hat is configured to start at boot but\u00a0MySQL<\/span><\/code>\u00a0isn\u2019t:<\/p>\n
\n
\n
[root@94 ~]# <\/span>chkconfig --list|<\/span>grep '3:on'<\/span>\r\nauditd          0:off   1:off   2:on    3:on    4:on    5:on    6:off<\/span>\r\ncrond           0:off   1:off   2:on    3:on    4:on    5:on    6:off<\/span>\r\nhttpd           0:off   1:off   2:on    3:on    4:on    5:on    6:off<\/span>\r\nip6tables       0:off   1:off   2:on    3:on    4:on    5:on    6:off<\/span>\r\niptables        0:off   1:off   2:on    3:on    4:on    5:on    6:off<\/span>\r\nlvm2-monitor    0:off   1:on    2:on    3:on    4:on    5:on    6:off<\/span>\r\nmessagebus      0:off   1:off   2:on    3:on    4:on    5:on    6:off<\/span>\r\nnetfs           0:off   1:off   2:off   3:on    4:on    5:on    6:off<\/span>\r\nnetwork         0:off   1:off   2:on    3:on    4:on    5:on    6:off<\/span>\r\nrsyslog         0:off   1:off   2:on    3:on    4:on    5:on    6:off<\/span>\r\nsendmail        0:off   1:off   2:on    3:on    4:on    5:on    6:off<\/span>\r\nsshd            0:off   1:off   2:on    3:on    4:on    5:on    6:off<\/span>\r\nsysstat         0:off   1:on    2:on    3:on    4:on    5:on    6:off<\/span>\r\nudev-post       0:off   1:on    2:on    3:on    4:on    5:on    6:off<\/span><\/pre>\n<\/div>\n<\/div>\n<\/section>\n","protected":false},"excerpt":{"rendered":"
Service Management on CentOS 6 On a Linux server, a service is an application that is capable of running in…<\/p>\n","protected":false},"author":1,"featured_media":10841,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[9],"tags":[],"class_list":["post-10840","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-linux"],"_links":{"self":[{"href":"https:\/\/www.webystrata.com\/blog\/wp-json\/wp\/v2\/posts\/10840","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.webystrata.com\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.webystrata.com\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.webystrata.com\/blog\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.webystrata.com\/blog\/wp-json\/wp\/v2\/comments?post=10840"}],"version-history":[{"count":2,"href":"https:\/\/www.webystrata.com\/blog\/wp-json\/wp\/v2\/posts\/10840\/revisions"}],"predecessor-version":[{"id":10843,"href":"https:\/\/www.webystrata.com\/blog\/wp-json\/wp\/v2\/posts\/10840\/revisions\/10843"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.webystrata.com\/blog\/wp-json\/wp\/v2\/media\/10841"}],"wp:attachment":[{"href":"https:\/\/www.webystrata.com\/blog\/wp-json\/wp\/v2\/media?parent=10840"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.webystrata.com\/blog\/wp-json\/wp\/v2\/categories?post=10840"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.webystrata.com\/blog\/wp-json\/wp\/v2\/tags?post=10840"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}