Description
string 
escapeshellcmd ( 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
   operator.
  
   Following characters are preceded by a backslash:
   #&;`|*?~<>^()[]{}$\, \x0A
   and \xFF. ' and "
   are escaped only if they are not paired. In Windows, all these characters
   plus % are replaced by a space instead.