Fwd: Re: interactive shell detection in shrc

[Steffen Nurpmeso <steffen%sdaoden.eu@localhost>]

--- Forwarded from Steffen Nurpmeso <steffen%sdaoden.eu@localhost> ---
Date: Tue, 24 Sep 2024 22:26:34 +0200
Author: Steffen Nurpmeso <steffen%sdaoden.eu@localhost>
From: Steffen Nurpmeso <steffen%sdaoden.eu@localhost>
To: Robert Elz <kre%munnari.OZ.AU@localhost>
Cc: Valery Ushakov <uwe%stderr.spb.ru@localhost>
Subject: Re: interactive shell detection in shrc
Message-ID: <20240924202634.-Z-0KGXP@steffen%sdaoden.eu>

Robert Elz wrote in
 <7132.1727161873%jacaranda.noi.kre.to@localhost>:
 |    Date:        Tue, 24 Sep 2024 00:56:40 +0200
 |    From:        Steffen Nurpmeso <steffen%sdaoden.eu@localhost>
 |    Message-ID:  <20240923225640.BZkYDiMv@steffen%sdaoden.eu>
 |
 || and then (in ~/.shrc)
 ||
 ||   eval "___isinc=\$___SHRC$$"
 ||   if [ -z "${___isinc}" ]; then
 ||           eval "___SHRC${$}=YES"
 ||           export ___SHRC${$}
 ||           case ${-} in
 ||           *i*|*m*) # {{{
 ||   ...
 ||           esac
 ||   fi
 ||   unset ___isinc
 |
 |Random suggestions, preceded by a question?
 |
 |Why are you exporting ___SHRC$$ ?    As long as this shell
 |continues running, there cannot be another process with the
 |same $$ so the include guard cannot possibly have any effect
 |anywhere else, and this shell doesn't need the variable to
 |be exported to see it.   By the time $$ is the same value in
 |some other shell, you want the .shrc processed, don't you?

That is a too logical thinking for the above.  I needed an include
guard, and it came out like that.  What you say sounds right.

 |Given that it doesn't need exporting, it also doesn't need
 |the $$ in its name either, so

..yes?!..

 | if $___SHRC

Oh, i would be afraid of doing this implicit test.  I no longer
have many shells around, not even as source code, so i would not
dare to do this.

 | then
 |  ___SHRC=false
 |  case $- in
 |  *i*|*m*)
 |   # whatever
 |   ;;
 |  *)
 |   # whatever else
 |   ;;
 |  esac
 |  # common stuff for all cases
 | fi
 |
 |If you insist on quoting the expansion in the first line,
 |it needs to become:
 |
 | if "${___SHRC:-:}"

A syntax error of yours?

 |even if you want too keep the $$ and export for some reason
 |
 | if eval "\$___SHRC$$"
 | then
 |  eval "___SHRC$$=false"
 |  export "___SHRC$$"
 |  # etc
 | fi
 |
 |with the similar variation if you want the ___SHRC$$ expansion
 |quoted:
 | if eval "\"\${___SHRC$$:-:}\""
 |

You do it once again?

 |kre
 |
 |ps: writing $$ (or any of the special params) as ${$} (etc)
 |is really taking things a little far, unless you want a more

Yes, but i had a (pretty long, as in years) period of time when
i was doing this.  It slowly comes to an end again.  (Unless
necessity for separation arises.)

 |complex expansion, like ${!:-$$} or something.   It is even
 |weirder when you write $$ in one place and ${$} in others
 |(and use $- rather than ${-}).   And of course using $# rather

Ja, the period came to an end, and i was not changing it all at
once.  That is uncommon (for me), but the file is usually private
and never looked at.
I also seem to keep -- from the public files -- the syntax that
was used when it was written.  However, looking at it, sometimes
there is a wild mixture of style in even the latest public thing,
the test of a DKIM signer.  Well...

 |than ${#} makes it clear that you want the number of set
 |positional params, and not the length of something that you
 |forgot to insert...

Hmmmm.  Well, i do not often take lengths in the shell, and if
then mostly in a right-hand-side.  Ok, i have looked, and i see
zero such constructs in all my public repositories as well as in
the misc.git that collects some stuff, and not in config.git.
$# is either argc, or used for patterns.  But i guess the ${}
syntax will vanish over time.

You know, it is much easier with a German keyboard to not use *any
of* {}[], ie, programming on a German keyboard is asking for
arthritis, except for languages going for mostly $() -- i never
really thought about this but was "beetling" over it, so to say,
but then i had an english aka american keyboard for some years,
and it was pretty neat, and over that i came to that kind of
super-explicit shell syntax.  And once the habit was adopted,
switching back to German keyboard did not change it for some
years; especially since on this laptop the "g" key stopped working
after a few weeks, and ever since i have to use

  keycode  41 = f F g G g G

via my

  [ -f ~/.${HOSTNAME}.xmodmaprc ] && xmodmap ~/.${HOSTNAME}.xmodmaprc

as well as

  #@ /root/hosts/self/system-hook

  if [ "${1}" = start ]; then
     echo 'loadkeys: adjusting G key'
     # dumpkeys/loadkeys
     /usr/bin/loadkeys <<-_EOT
          altgr keycode 33 = g
          alt keycode 33 = g
          shift alt keycode 33 = G
          shift altgr keycode 33 = G
     _EOT
  fi

so that is a nice level of finger acrobatics anyway.  Well.
Cool laptop, i love it.  512GB NVME disk, unbelievable.

 --End of <7132.1727161873%jacaranda.noi.kre.to@localhost>

--steffen
|
|Der Kragenbaer,                The moon bear,
|der holt sich munter           he cheerfully and one by one
|einen nach dem anderen runter  wa.ks himself off
|(By Robert Gernhardt)

 -- End forward <20240924202634.-Z-0KGXP@steffen%sdaoden.eu>

--steffen
|
|Der Kragenbaer,                The moon bear,
|der holt sich munter           he cheerfully and one by one
|einen nach dem anderen runter  wa.ks himself off
|(By Robert Gernhardt)