为什么我得到一个分段错误，当我Exec的＆QUOT; PM＆QUOT;在Android设备？

我的设备：htcg14根

my device:htcg14 rooted

我可以Exec的模拟器上下午。

i can exec pm on emulator.

但我的设备无法正常工作。 之前我Exec的苏，它工作正常。

But my device does not work. Before I exec "su",it works fine.

shell@android:/ $ pm
usage: pm list packages [-f] [-d] [-e] [-s] [-e] [-u] [FILTER]
       pm list permission-groups
       pm list permissions [-g] [-f] [-d] [-u] [GROUP]

但是，当我Exec的苏，那么EXEC时，我得到一个错误below.Why？

But when I exec su,then exec pm,i get an error below.Why?

shell@android:/ $ su
su
shell@android:/ # pm
pm
[1] + Stopped (signal)     pm
shell@android:/ # pm
pm
[2] + Stopped (signal)     pm
[1] - Segmentation fault   pm
shell@android:/ # busybox pm
busybox pm
pm: applet not found
[2] + Segmentation fault   pm
1|shell@android:/ #

我怎么能执行时？ 帮助...

how can i execute pm? help...