Upgrading all packages on OpenWrt with the
opkg command isn’t possible. There is no
opkg upgrade --all command or anything similar.
opkg upgrade expects a package as the first parameter that then gets upgraded. But with a little bash scripting we can easily implement the behavior we want (upgrade all the packges).
for pkg in `opkg list-upgradable | cut -d' ' -f1` | grep -v Multiple; do opkg upgrade $pkg; done
It wouldn’t advise doing an upgrade like this. The best way is still to individually upgrade each package and read the upgrade notes.