I have compiled C code running as a binary on an ARM. The ARM boots Linux from an SD Card using an old Image that was generated using buildroot. Within the C code I call a shell script that moves the new Image I want to boot with from a sub-directory on the SD Card onto the top level of the SD Card (overwriting the old Image), and then use the backup Image.bak to restore the Image in the sub-directory again, in case I run the script again:
#!/bin/sh
mv /sd/newImage/Image /sd/
mv /sd/newImage/Image.bak /sd/newImage/Image
reboot
The reboot works properly in this case (Putty disconnects -> the LED on the board I'm using goes Red then Green -> I can reconnect through Putty), although the second mv command does not - it removes the Image.bak but does not create an Image - but that is not the purpose of this post, really.
When I try to modify the script so that the Image.bak does actually restore the Image by using the cp command, then the reboot does not work properly.
#!/bin/sh
mv /sd/newImage/Image /sd/
cp /sd/newImage/Image.bak /sd/newImage/Image
reboot
What happens is the Putty terminal I was using disconnects, but the LED on the board that goes red when signaling it is rebooting just stays green and the only way to re-establish a connection through Putty is to manually power cycle the board via the power switch. So it seems that there is something weird happening when I call the cp command in the shell script. I have tried umount /sd and using sync before the reboot thinking that maybe there was syncing issues, but that didn't work either.
I am logged in as root, and the permissions should not be an issue with any of this.
