int chmod(string filename, int mode);Attempts to change the mode of the file specified by filename to that given in mode.
Note that mode is not automatically assumed to be an octal value. To ensure the expected operation, you need to prefix mode with a zero (0):
chmod( "/somedir/somefile", 755 ); // decimal; probably incorrect
chmod( "/somedir/somefile", 0755 ); // octal; correct value of mode
Returns true on success and false otherwise.