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The name of the unit doesn't really matter, as the syntax of the 
systemctl
 command 
is the same regardless of the name of the unit we're interacting with. You can use 
systemctl
 to start, stop, or restart your Apache instance, your database server, or 
even use it to restart the entire networking stack. The 
systemctl
 command, with no 
options or parameters, assumes the 
list-units
 option, which dumps a list of units to 
your shell. This can be a bit messy, though, so if you already know the name of a unit 
you'd like to search for, you can pipe the output into 
grep
 and search for a string. 
This is handy in a situation where you may not know the exact name of the unit, but 
you know part of it:
systemctl |grep ssh 
If you want to check the health of a unit, the best way is to actually use the 
status
 
keyword, which will show you some very useful information regarding the unit. 
This information includes whether or not the unit is running, if it's enabled (meaning 
it's configured to start at boot time), as well as the most recent log entries for the unit:
systemctl status ssh 
This command will produce an output something like the following:
Figure 7.9: Checking the status of a unit with systemctl
Most of the time, you can actually check the status of units without needing 
root
 
access, but you may not see all the information available. In the screenshot, you can 
see several log entries for the 
ssh
 service, but some units do not show those entries 
without 
sudo
. With the 
ssh
 unit in particular, we see the log entries when checking 
the status with or without 
sudo
.

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Chapter 7