sh 中source 不可用

oneplus@oneplus-OptiPlex-9020:~/work/MSM8996/android$ ls `which sh` -l
lrwxrwxrwx 1 root root 4  4月  8  2015 /bin/sh -> dash
oneplus@oneplus-OptiPlex-9020:~/work/MSM8996/android$ mv /bin/sh /bin/sh-dash 　以后复原
mv: 无法将"/bin/sh" 移动至"/bin/sh-dash": 权限不够
oneplus@oneplus-OptiPlex-9020:~/work/MSM8996/android$ sudo mv /bin/sh /bin/sh-dash
[sudo] password for oneplus:
oneplus@oneplus-OptiPlex-9020:~/work/MSM8996/android$ sudo ln -s /bin/bash  /bin/sh
oneplus@oneplus-OptiPlex-9020:~/work/MSM8996/android$