what is the standard editor in Android? I'm connecting to this Google phone via adb, I need to change a character inside of a text file, and I would use vi, or maybe sed -i, or even pico if nothing else helps, but I don't find any well known CLI editor.

how do you Android Enthusiasts do this?  I mean, short of copying the file back and forth?

root@generic_x86:/ # vi
/system/bin/sh: vi: not found
127|root@generic_x86:/ # pico
/system/bin/sh: pico: not found
127|root@generic_x86:/ # nano
/system/bin/sh: nano: not found
127|root@generic_x86:/ # vim
/system/bin/sh: vim: not found
127|root@generic_x86:/ # sed
/system/bin/sh: sed: not found
127|root@generic_x86:/ # emacs
/system/bin/sh: emacs: not found
127|root@generic_x86:/ # apropos editor
/system/bin/sh: apropos: not found
127|root@generic_x86:/ #
As mentioned, I would be happy with sed.
Still as later mentioned in a comment, I am in a virtual environment, so no trouble dropping one OS and start using the newer one.

Apparently, my problem was staying in Android 5.1.  Starting version 6 Android includes ToyBox, a rather limited alternative to BusyBox, legally compatible with the non-free license of Android.

The ToyBox hint comes from the author of droidvim.