<?php 
$test = "ls /tmp/test"; //ls是linux下的查目录，文件的命令
exec($test,$array); //执行命令
print_r($array);
?>

[root@krlcgcms01 shell]# php ./exec.php 
Array 
( 
[0] => 1001.log 
[1] => 10.log 
[2] => 10.tar.gz 
[3] => aaa.tar.gz 
[4] => mytest 
[5] => test1101 
[6] => test1102 
[7] => weblog_2010_09 
)

<?php 
$test = "ls /tmp/test";
$last = system($test);
print "last: $last\n";
?>

[root@krlcgcms01 shell]# php system.php 
1001.log 
10.log 
10.tar.gz 
aaa.tar.gz 
mytest 
test1101 
test1102 
weblog_2010_09 
last:weblog_2010_09

<?php 
$test = "ls /tmp/test";
passthru($test);
?>

<?php 
$test = "ls /tmp/test";
$fp = popen($test,"r"); //popen打一个进程通道

while (!feof($fp)) { //从通道里面取得东西
$out = fgets($fp, 4096);
echo $out; //打印出来
} 
pclose($fp);
?>

<?php 
$test = "ls /tmp/test";
$array = array(
array("pipe","r"), //标准输入 
array("pipe","w"), //标准输出内容 
array("pipe","w") //标准输出错误 
); 
$fp = proc_open($test,$array,$pipes); //打开一个进程通道
echo stream_get_contents($pipes[1]); //为什么是$pipes[1]，因为1是输出内容
proc_close($fp);
?>

<?php 
$test = "ls /tmp/test";
$out = shell_exec($test);
echo $out;
?>

[root@krlcgcms01 shell]# php test.php 
1001.log 
10.log 
10.tar.gz 
aaa.tar.gz 
mytest 
test1101 
test1102 
weblog_2010_09