I'm going to blog about Splunk CLI commands. By the way I'm going to check if fifo input is discontinued. Meanwhile lets talk about some basic CLI commands now.
 There are several basic commands and it may take a while to cover all of them. I'll try going case by case such as say for a given task at hand. This way we will know how to use it. Again, there's plenty of literature on docs.splunk.com but my goal here is to mention the ones I've used.
Here's a command to register perfmon. You can modify the inputs.conf file with the details of the perfmon config
splunk add exec scripts\splunk-perfmon.path -interval 60
and splunk enable perfmon
The CLI commands are based on verbs and objects.
You can start or stop splunk with : splunk start splunkd --debug
 but you can only do that with splunkd and splunkweb.  Also, since we are talking about perfmon events, we can use the CLI to see what perfmon will be collecting with our command:
splunk list perfmon
In this case, it will give you output such as :
Monitored Perfmon Collections:
        LogicalDisk
                _TCP_ROUTING:windowsIndex
                counters:*
                disabled:0
                host:RRAJAMANIPC
                index:windows_perfmon
                interval:10
                object:LogicalDisk
These are what we define in the inputs.conf file.
Note that individual perfmon items can also be enabled or disabled separately
splunk enable perfmon LogicalDisk
and similarly we can disable them individually as follows:
splunk disable perfmon LogicalDisk
CLI commands enable to activate a configuration change with the reload command as
splunk reload perfmon which makes it effective immediately.