Read only file system on Android

Not all phones and versions of android have things mounted the same.
Limiting options when remounting would be best.

Simply remount as rw (Read/Write):

# mount -o rw,remount /system

Once you are done making changes, remount to ro (read-only):

# mount -o ro,remount /system

Got this off an Android forum where I asked the same question. Hope this helps somebody else.

On a terminal emulator on the phone:

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

Then on the cmd prompt, do the adb push

adb remount

works for me and seems to be the simplest solution.