After dropping support for 18.06 I`m flash 19.07. Now every time when try "opkg list-upgradable" in terminal I have error "out of memory". I searched a little and found out that 32MB RAM is too small for this operation. Because this list requires at least 64MB. Ok. But why then Luci updates packages without problems? I'm confused.
Is there any way to use "opkg list-upgradable" on router with 19.07 and 32MB RAM? For example, reduce this list. I am not installing any additional packages. I only need security updates for already preinstalled packages.
32 MB RAM is pretty much too little for anything with 19.07.x. The kernel size has grown along the years, and all needed stuff barely fits into the router.
I know all this. But everything works fine (even development snapshot builds) except for updating packages. And what I don't understand at all is why Luci can still update packages when openssh client can not.
Luci no longer calls opkg directly and uses a more memory efficient shell script for some operations. list-upgradeable doesn't seem to be one of them, but list-available is, which likely performs a similar action (upgrades + new installs)
Upgrading packages (via the CLI opkg upgrade command or the LuCI Upgrade... button) can result in major problems. It is generally highly discouraged, unless you know what you are doing or if there is specific instruction to do so.
Ok... just wanted to make sure you are aware of the risk. Be sure to have a good backup at all times before you run any upgrades, of course, so that if something does get messed up, you have an easy/fast recovery option.
There are some users here, including some long-time 'regulars' who share your experience of never actually having a problem with the opkg upgrade process. And there are others who have had really bad luck. The warning is there because nobody is exactly sure why some of these issues crop up and we want to make sure that people are forewarned. But sounds like you're probably in good shape thus far, aside from the specific issue you've raised with the OP.