( string command )
escapeshellcmd() escapes any characters in a
string that might be used to trick a shell command into executing
arbitrary commands. This function should be used to make sure
that any data coming from user input is escaped before this data
is passed to the exec() or
system() functions, or to the backtick
Following characters are preceded by a backslash:
and \xFF. ' and "
are escaped only if they are not paired. In Windows, all these characters
plus % are replaced by a space instead.