A terminal command for a rooted Android to remount /System as read/write

Question

I'm writing an android app that needs to copy a file to the "/system" partition at runtime. I've got the commands to run "su" and can successfully request SuperUser permissions and run commands as root. But I don't know how to make this app universal across multiple devices, because the mount command can differ depending on where the /system is actually mounted. Here's the command that's used most offen:

mount -o remount,rw -t yaffs2 /dev/block/mtdblock3 /system 

But I know that mtdblock3 could be different on some devices (and for that matter, i guess so could yaffs2). So, my question is: Is there a universal command that will work on all phones? Or is there a way to find out at runtime what the correct parameters are?

Answer 1

I use this command:

mount -o rw,remount /system 

Answer 2

You can run the mount command without parameter in order to get partition information before constructing your mount command. Here is an example of the mount command without parameter outputed from my HTC Hero.

$ mount mount rootfs / rootfs ro 0 0 tmpfs /dev tmpfs rw,mode=755 0 0 devpts /dev/pts devpts rw,mode=600 0 0 proc /proc proc rw 0 0 sysfs /sys sysfs rw 0 0 tmpfs /sqlite_stmt_journals tmpfs rw,size=4096k 0 0 none /dev/cpuctl cgroup rw,cpu 0 0 /dev/block/mtdblock3 /system yaffs2 rw 0 0 /dev/block/mtdblock5 /data yaffs2 rw,nosuid,nodev 0 0 /dev/block/mtdblock4 /cache yaffs2 rw,nosuid,nodev 0 0 /dev/block//vold/179:1 /sdcard vfat rw,dirsync,nosuid,nodev,noexec,uid=1000,gid= 1015,fmask=0702,dmask=0702,allow_utime=0020,codepage=cp437,iocharset=iso8859-1,s hortname=mixed,utf8,errors=remount-ro 0 0