PHP supports one execution operator: backticks (``). Note that
these are not single-quotes! PHP will attempt to execute the
contents of the backticks as a shell command; the output will be
returned (i.e., it won't simply be dumped to output; it can be
assigned to a variable). Use of the backtick operator is identical
to shell_exec().
See also the manual section on Program
Execution functions, popen()
proc_open(), and
Using PHP from the
commandline.
