exec
(PHP 4, PHP 5)
exec — Execute an external program
Description
string exec
( string $command
[, array &$output
[, int &$return_var
]] )
Parameters
-
command
-
The command that will be executed.
-
output
-
If the output
argument is present, then the
specified array will be filled with every line of output from the
command. Trailing whitespace, such as \n, is not
included in this array. Note that if the array already contains some
elements, exec() will append to the end of the array.
If you do not want the function to append elements, call
unset() on the array before passing it to
exec().
-
return_var
-
If the return_var
argument is present
along with the output
argument, then the
return status of the executed command will be written to this
variable.
Return Values
The last line from the result of the command. If you need to execute a
command and have all the data from the command passed directly back without
any interference, use the passthru() function.
To get the output of the executed command, be sure to set and use the
output
parameter.
Examples
Example #1 An exec() example
<?php
// outputs the username that owns the running php/httpd process
// (on a system with the "whoami" executable in the path)
echo exec('whoami');
?>
Notes
WarningWhen allowing user-supplied data to be
passed to this function, use
escapeshellarg() or escapeshellcmd()
to ensure that users cannot trick the system into executing arbitrary
commands.
Note: If a program is started with this function,
in order for it to continue running in the background, the output of the
program must be redirected to a file or another output stream. Failing to do so
will cause PHP to hang until the execution of the program ends.
Note: When
safe mode is enabled, you can only
execute files within the safe_mode_exec_dir.
For practical reasons, it is currently not allowed to have ..
components in the path to the executable.
WarningWith safe mode enabled,
the command string is escaped with escapeshellcmd(). Thus,
echo y | echo x becomes echo y \| echo x.
