Tuesday, October 17, 2017

Red Hat / CentOS: Check / List Running Services

How do I list all currently running services in Fedora / RHEL / CentOS Linux server?

There are various ways and tools to find and list all running services under Fedora / RHEL / CentOS Linux systems.

service command – list running services

The syntax is as follows for CentOS/RHEL 6.x and older (pre systemd):
service --status-all
service --status-all | more
service --status-all | grep ntpd
service --status-all | less

Print the status of any service

To print the status of apache (httpd) service:
service httpd status

List all known services (configured via SysV)

chkconfig --list

List service and their open ports

netstat -tulpn

Turn on / off service

ntsysv
chkconfig service off
chkconfig service on
chkconfig httpd off
chkconfig ntpd on

ntsysv is a simple interface for configuring runlevel services which are also configurable through chkconfig. By default, it configures the current runlevel. Just type ntsysv and select service you want to run.

A note about RHEL/CentOS 7.x with systemd

If you are using systemd based distro such as Fedora Linux v22/23/24 or RHEL/CentOS Linux 7.x+. Try the following command to list running services using the systemctl command. It control the systemd system and service manager.

To list systemd services on CentOS/RHEL 7.x+ use

The syntax is:
systemctl
systemctl | more
systemctl | grep httpd
systemctl list-units --type service
systemctl list-units --type mount

To list all services:
systemctl list-unit-files
Sample outputs:
Fig.01: List all units installed on the CentOS /RHEL 7 systemd based system, along with their current states
Fig.01: List all units installed on the CentOS /RHEL 7 systemd based system, along with their current states

To view processes associated with a particular service (cgroup), you can use the systemd-cgtop command. Like the top command, systemd-cgtop lists running processes based on their service:
systemd-cgtop
Sample outputs:
Path                                            Tasks   %CPU   Memory  Input/s Output/s
 
/                                                  85    0.3   240.1M        -        -
/system.slice/NetworkManager.service                2      -        -        -        -
/system.slice/auditd.service                        1      -        -        -        -
/system.slice/crond.service                         1      -        -        -        -
/system.slice/dbus.service                          1      -        -        -        -
/system.slice/lvm2-lvmetad.service                  1      -        -        -        -
/system.slice/polkit.service                        1      -        -        -        -
/system.slice/postfix.service                       3      -        -        -        -
/system.slice/rsyslog.service                       1      -        -        -        -
/system.slice/sshd.service                          1      -        -        -        -
/system.slice/...tty.slice/getty@tty1.service       1      -        -        -        -
/system.slice/systemd-journald.service              1      -        -        -        -
/system.slice/systemd-logind.service                1      -        -        -        -
/system.slice/systemd-udevd.service                 1      -        -        -        -
/system.slice/tuned.service                         1      -        -        -        -
/system.slice/wpa_supplicant.service                1      -        -        -        -
/user.slice/user-0.slice/session-2.scope            1      -        -        -        -
/user.slice/user-1000.slice/session-1.scope         4      -        -        -        -

To list SysV services only on CentOS/RHEL 7.x+ use (does not include native systemd services)

chkconfig --list
Sample outputs:
Fig.02: List Sysv based services on systemd
Fig.02: List Sysv based services on systemd

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