(string command, string mode);
Opens a pipe to a process executed by forking the command given
Returns a file pointer identical to that returned by
fopen(), except that it is unidirectional (may
only be used for reading or writing) and must be closed with
pclose(). This pointer may be used with
fgets(), fgetss(), and
If an error occurs, returns false.
2 $fp = popen ("/bin/ls", "r");
See also pclose().