PHP shell_exec() vs exec()

shell_exec() 和 exec()的区别是什么？

shell_exec

returns all of the output stream as a string.

exec

returns the last line of the output by default, but can provide all output as an array specifed as the second parameter.

See

• http://php.net/manual/en/function.shell-exec.php
  
• http://php.net/manual/en/function.exec.php
  

Here are the differences. Note the newlines at the end.

> shell_exec('date')
string(29) "Wed Mar  6 14:18:08 PST 2013\n"
> exec('date')
string(28) "Wed Mar  6 14:18:12 PST 2013"

> shell_exec('whoami')
string(9) "mark\n"
> exec('whoami')
string(8) "mark"

> shell_exec('ifconfig')
string(1244) "eth0      Link encap:Ethernet  HWaddr 10:bf:44:44:22:33  \n  TX bytes:2779457335 (2.7 GB)\n"...
> exec('ifconfig')
string(0) ""

exec('ls', $out);
var_dump($out);
// Look an array

$out = shell_exec('ls');
var_dump($out);
// Look -- a string with newlines in it

exec('ls', $out, $status);
if (0 === $status) {
    var_dump($out);
} else {
    echo "Command failed with status: $status";
}