pcntl_exec() executes the program path with arguments args. path must be the path to a binary executable or a script with a valid path pointing to an executable in the shebang ( #!/usr/local/bin/perl for example) as the first line. See your system's man execve(2) page for additional information.
args is an array of argument strings passed to the program.
envs is an array of strings which are passed as environment to the program. The array is in the format of name => value, the key being the name of the environmental variable and the value being the value of that variable.
pcntl_exec() returns FALSE on error and does not return on success.