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Why does st not handle utmp entries?

Use the excellent tool of utmp[0] for this task.

[0] http://git.suckless.org/utmp/
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Some _random program_ complains that st is unknown/not
recognised/unsupported/whatever!

It means that st doesn’t have any terminfo entry on your system. Chances are
you did not make install. If you just want to test it without installing it,
you can manualy run tic -s st.info in st dir. It will compile st.info into a
fully working local terminfo description. You can delete it when you’re done.
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Nothing works, and nothing is said about an unknown terminal!

* Some programs just assume they’re running in xterm i.e. they don’t rely on
  terminfo. What you see is the current state of the “xterm compliance”.
* Some programs don’t complain about the lacking st description and default to
  another terminal. In that case see the question about terminfo.
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I get some weird glitches/visual bug on _random program_!

Try lauching it with a different TERM: $ TERM=xterm myapp. toe(1) will give
you a list of available terminals, but you’ll most likely switch between
xterm, st or st-256color. The default value for TERM can be changed in
config.h (TNAME).
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How do I scroll back up?

Invoke st with a screen multiplexer like GNU screen[0] or tmux[1].
st -e screen works better for text reflowing. To enter screen’s scroll
back mode aka “copy mode”, it’s C-a ESC. You probably want defscrollback
10000 in your ~/.screenrc too.

[0] http://en.wikipedia.org/wiki/GNU_Screen
[1] http://en.wikipedia.org/wiki/Tmux
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