system x system[x]
Where x is a string representing a system command
and any parameters to it, executes the command and returns any result.
q)\l sp.q
…
q)\a / tables in namespace
`p`s`sp
q)count \a / \ must be the first character
'\
q)system "a" / same command called with system
`p`s`sp
q)count system "a" / this returns a result
3
As with \, if the argument is not a q command, it is executed in the shell:
q)system "pwd"
"/home/guest/q"