RHCE Learning Notes (+) Target Service

This section is relatively simple, learning the Target service inside the RHEL7.

Inside the RHEL7, the initial process becomes systemd. RHEL6 and previous versions used the initial process is Init,init is a linear start-up process, one after the start, relatively slow, systemd can be multi-process startup, the speed is much higher. In addition, SYSTEMD has the advantages of simplifying development and integrating logs.

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When learning Systemctl, the specific service at the end of the services can perform operations such as Start,stop,restart, and there is a class suffix that ends with target, which can be treated as a collection of services. Which services are pre-defined and which do not run. This concept is very similar to the concept of runlevel before the RHEL6 level.

View Target Service

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RHEL6 before the version, you can see in the/ETC/RC.D 7 RunLevel, each operating level corresponding to different functions, such as 0 is shutdown, 1 is a single user, 2 is multi-user (no network), 3 is multi-user, 4 useless, 5 is a graphical interface, 6 is a reboot. You can use init 0 to shut down the computer directly, and so on.

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RHEL7, Target has a similar definition.

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Legacy commands such as RunLevel and Init are still compatible, such as viewing the current target (runlevel), and I can also view the default target (RunLevel)

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Similar switching runlevel can be used with init or systemctl isolate.

For example, switch to the command line interface

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If I enter init 5 or STARTX, I can switch directly to the graphical interface.

RHCE Learning Notes (+) Target Service