os.system() 和 os.popen()
1. os.system()
os.system 直接执行命令，执行成功返回0.
>>> a = os.system('ls')
bin dev initrd.img lib32 media proc scratch sys var
boot etc initrd.img.old lib64 mnt root selinux tmp vmlinuz
cdrom home lib lost+found opt sbin srv usr vmlinuz.old
>>> a
0
2. os.popen()
os.popen() 将运行结果作为一个 file object 返回。
>>> a = os.popen('ls')
>>> a
<open file 'ls', mode 'r' at 0x7f866451ddb0>
>>> a.readlines()
['bin ', 'boot ', 'cdrom ', 'dev ', 'etc ', 'home ', 'initrd.img ', 'initrd.img.old ', 'lib ', 'lib32 ', 'lib64 ', 'lost+found ', 'media ', 'mnt ', 'opt ', 'proc ', 'root ', 'sbin ', 'scratch ', 'selinux ', 'srv ', 'sys ', 'tmp ', 'usr ', 'var ', 'vmlinuz ', 'vmlinuz.old ']