Occasionally, you need a list of packages installed on OpenWrt. The standard opkg list-installed is great, except it lists package versions in addition to package names. So if you need to list names only, here's what you can do.

To show each name on a new line:

opkg list-installed | cut -f 1 -d ' '

To output all names as one long line:

opkg list-installed | awk '{ printf "%s ",$1 }'