Previous versions of Oracle Linux use init scripts located in the \/etc\/rc.d\/init directory to start and stop services. In RHEL 7, these init scripts have been replaced with systemd service units. Service units have a .service extension. Use the systemctl command to list all loaded service units:<\/p>\n
# systemctl list-units –type service –all
\nUNIT LOAD ACTIVE SUB DESCRIPTION
\nauditd.service loaded active running Security Auditing Service
\navahi-daemon.service loaded active running Avahi mDNS\/DNS-SD Stack
\n…..
\nHere,
\nLOAD \u2013 service load state
\nhigh-level (ACTIVE) and low-level (SUB) unit activation state
\nDESCRIPTION \u2013 description of the service unit.<\/p>\n
Omit the \u2013all option to list only the active service units. Use the list-unit-files option to see which service units are enabled:<\/p>\n
# systemctl list-unit-files –type service<\/p>\n
Displaying status of the services<\/p>\n
systemd service units correspond to system services. Use the following command to display detailed information about a service unit. This example displays information about the sshd service unit.<\/p>\n
# systemctl status sshd<\/p>\n
The following information is available for the specified service unit:<\/p>\n
Loaded: If the service is loaded, the absolute path to the service unit file, and if the
\nservice unit is enabled
\nActive: If the service unit is running and a timestamp
\nMain PID: The Process ID of the corresponding system service and the service name
\nStatus: Additional information about the corresponding system service
\nProcess: Additional information about related processes
\nCGroup: Additional information about related Control Groups
\nTo check whether a service is running (active) or not running (inactive):<\/p>\n
# systemctl is-active sshd
\nactive
\nTo check whether a service is enabled:<\/p>\n
# systemctl is-enabled sshd
\nenabled
\nStarting and Stopping Services<\/p>\n
In previous versions of RHEL, the service utility is used to stop and start services. In RHEL 7, the systemctl utility provides an equivalent set of subcommands. The table below shows a comparison of the service utility with systemctl.<\/p>\n
SERVICE UTILITY\tSYSTEMCTL UTILITY\tDESCRIPTION
\nservice name start\tsystemctl start name\tStarts a service
\nservice name stop\tsystemctl stop name\tStops a service
\nservice name restart\tsystemctl restart name\tRestarts a service
\nservice name condrestart\tsystemctl try- restart name\tRestarts a service only if it is running
\nservice name reload\tsystemctl reload name\tReloads a configuration
\nservice name status\tsystemctl status name\tChecks whether a service is running
\nservice \u2013status- all\tsystemctl list-units \u2013type service \u2013all\tDisplays the status of all services
\nEnabling and disabling services<\/p>\n
In previous versions of RHEL, the chkconfig utility is used to enable and disable services. In RHEL 7, the systemctl utility provides an equivalent set of subcommands. The table below shows a comparison of the chkconfig utility with systemctl.<\/p>\n
CHKCONFIG UTILITY\tSYSTEMCTL UTILITY\tDESCRIPTION
\nchkconfig name on\tsystemctl enable name\tEnables a service
\nchkconfig name off\tsystemctl disable name\tDisables a service
\nchkconfig \u2013list name\tsystemctl status name, systemctl is-enabled name\tChecks whether a service is enabled
\nchkconfig \u2013list\tsystemctl list-unit-files \u2013type service\tLists all services and checks whether they are enabled<\/p>\n","protected":false},"excerpt":{"rendered":"
Previous versions of Oracle Linux use init scripts located in the \/etc\/rc.d\/init directory to start and stop services. In RHEL 7, these init scripts have been replaced with systemd service units. Service units have a .service extension. Use the systemctl command to list all loaded service units:<\/p>\n
# systemctl list-units –type service –all UNIT LOAD […]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[73],"tags":[],"_links":{"self":[{"href":"https:\/\/mohan.sg\/index.php?rest_route=\/wp\/v2\/posts\/6716"}],"collection":[{"href":"https:\/\/mohan.sg\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/mohan.sg\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/mohan.sg\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/mohan.sg\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=6716"}],"version-history":[{"count":1,"href":"https:\/\/mohan.sg\/index.php?rest_route=\/wp\/v2\/posts\/6716\/revisions"}],"predecessor-version":[{"id":6717,"href":"https:\/\/mohan.sg\/index.php?rest_route=\/wp\/v2\/posts\/6716\/revisions\/6717"}],"wp:attachment":[{"href":"https:\/\/mohan.sg\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=6716"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/mohan.sg\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=6716"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/mohan.sg\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=6716"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}