base-files version
opkg list-installed base-files | awk -v FS="-" '{print $4}'
/etc/banner (may fail if not trunk)
awk -v FS="[ )]" '/r[0-9]+/ {print $5}' /etc/banner
/etc/banner
awk 'match($0,/r[0-9]+/) {print substr($0,RSTART,RLENGTH)}' /etc/banner
All of the above outputs the same:
r25094
Any shorter method?