S9 LIB  (spawn-shell-command string)     ==>  list
        (spawn-shell-command/fd string)  ==>  list

        (load-from-library "spawn-shell-command.scm")

Spawn a child process running the shell command STRING. Return
a list of two I/O-ports and the PID of the child process:

        (input-port output-port integer)

The input-port can be used to read the output of the command and
the output-port to send input to the command. The command will be
executed by running the equivalent of:

        execl("/bin/sh", "/bin/sh", "-c", STRING, NULL);

Error output of the child will be redirected to its standard output.

SPAWN-SHELL-COMMAND/FD is like SPAWN-SHELL-COMMAND, but delivers raw
Unix file descriptors instead of input/output ports.

(spawn-shell-command "ls -l /bin")
  ==>  (#<input-port> #<output-port> 707)
