Hello, there.
I want to install package on webOS running time.
But I can't find package manager command like apt-get, dpkg, rpm, npm, pip...
And I saw many official document. They said you must include the package you want before building the webOS.
I used an already builded image. Because my host computer was too slow to 'build images'.
Can I install package after build image? (opencv, gcc ...)
The bottom line is that you have to build package to use it. (in most cases) A good news is that webOS OSE already contains opencv. After doing a few steps, you can use opencv in webOS OSE. See Using OpenCV in webOS OSE.
We're not running a binary seed server for webOS OSE. So webOS OSE doesn't support command such as apt-get.
Instead, webOS OSE supports opkg command, it enables to install .ipk files (which is built for webOS OSE) to your own webOS OSE.
opkg install <package-name>.ipk
But a way to make the .ipk file is not quite easy, especially who are not familiar with Yocto Project. You need to know how to set up build environment, write CMake file, and so on. I give you some tutorials about basics, but you might need to study more about the Yocto project.