system - issue a shell command
If the string argument is the NULL pointer (0) the function tests the
accessibility of the command interpreter The function will return zero
for failure to find the command interpreter, and positive if success‐
If the string argument is non-NULL the routine causes the string to be
given to as input as if the string had been typed as a command at a
terminal. The current process waits until the shell has completed,
then returns the exit status in the form that returns.
Exit status 127 indicates the shell couldn't be executed.
See Alsoexecve(2), wait(2), popen(3)system(3)