#!/usr/bin/env tsh
:
: tsh - " Force sh(1), csh(1), and other shells to exit w/ error! " <'' ;;;
:
: "  @(#)$Id: ifzyon,v 1.3 2018/12/15 07:09:42 jneitzel Exp $
:
: "  The author of this file, J.A. Neitzel <jan (at) etsh (dot) nl>,  "
: "  hereby grants it to the public domain.                           "
:

:
: "  This tsh script (aka command file) illustrates shell voodoo! =^)  "
:
: "  Do `if -z string' & `if -n string', where string is specified  "
: "  by $1.  As noted by the usage message below though, string is  "
: "  in fact optional (for this script, but not for if(1)).         "
:
: "  usage: ifzyon [string]  "
:

: >>$0'' <'' ; : >>$1'' <''

if ! { mkdir -m 0700 /tmp/ifzyon-$$ } if { exit } false

( : ) > /tmp/ifzyon-$$/expr
( \
  echo echo -n \''The specified string "'$1'" is '\' ; \
  echo -n expr '"//'$1'" : '\''//.*'\'' - 2 | ' ; \
  echo tr -d '\\n' ; \
  echo echo '\ character\(s\) in length.' \
) >> /tmp/ifzyon-$$/expr
: fd2 -e cat /tmp/ifzyon-$$/expr
tsh /tmp/ifzyon-$$/expr
echo

( : ) > /tmp/ifzyon-$$/run
( \
  echo -n if -z ; \
  echo -n \ \"$1\" ; \
  echo    \ echo '\	'-z: The length of '\"'$1'\"' is zero. \
) >> /tmp/ifzyon-$$/run
( \
  echo -n if -n ; \
  echo -n \ \"$1\" ; \
  echo    \ echo '\	'-n: The length of '\"'$1'\"' is non-zero. \
) >> /tmp/ifzyon-$$/run

: fd2 -e cat /tmp/ifzyon-$$/run
< /tmp/ifzyon-$$/run ( rm -r /tmp/ifzyon-$$ ; tsh - )
: zero status