21 Jan
2020
21 Jan
'20
1:40 a.m.
On Mon, Jan 20, 2020 at 09:15:56AM +0100, markus schnalke wrote:
Hoi.
[2020-01-19 14:22] Grant Taylor via TUHS <tuhs(a)minnie.tuhs.org>
<Raises hand>
The normal reason why I'm starting subshells is because I need to
control various environment variables on an ad-hoc basis. It might be
PYTHONPATH, KRB5CCNAME, GPG_AGENT_INFO, LD_LIBRARY_PATH, or some
combination of the above. Back when I was regularly using Kerberos
root/admin bits, I had some hard-coded shell aliases to indicate
explicitly I was in a shell that was using my
tytso/root(a)ATHENA.MIT.EDU or tytso/admin(a)ATHENA.MIT.EDU kerberos
tickets.
But for ad-hoc use cases, SHLVL is great way to track whether I'm a
non-standard shell environment. For me, some use case probably comes
up at least week or two.
Have you ever used shell level, $SHLVL, in your weekly ~> daily use of Unix?
What's the use of it? The only use of $SHLVL I can think of is the
answer to the question if ^D will close the last shell or just a
sub shell. I hardly ever ask myself this question. Probably that
starts to become relevant when you open sub shells frequently. With tmux or screen at hand, this use case is obsolete
for me.
(Besides, my shell doesn't know about $SHLVL.)
Before I was using bash regularly, I had hard-coded something like
SHLVL in my .tcshrc.
- Ted