Touch won't error it will just update the date and time the file was modified to 'now'
[nemo@Sailfish ~]$ touch /opt/alien/data/app/com.android.vending-1.apk touch: cannot touch `/opt/alien/data/app/com.android.vending-1.apk': Permission denied [nemo@Sailfish ~]$ devel-su Password: [root@Sailfish nemo]# touch /opt/alien/data/app/com.android.vending-1.apk touch: cannot touch `/opt/alien/data/app/com.android.vending-1.apk': Permission denied [root@Sailfish nemo]#