What value can not be changed in /proc/sys?
echo "Windows" > /proc/sys/kernel/ostype bash: /proc/sys/kernel/ostype: Permission denied
Because ostype don't have write permission:
If file in /proc/sys/ have write permission, you can change values in it.
The real answer to this question is really to understand what the proc filesystem means.
Thus yes the basic answer to 'why can't I write to