#!/usr/bin/env tsh
:
: tsh - " Force sh(1), csh(1), and other shells to exit w/ error! " <'' ;;;
:
: "  @(#)$Id: ifzyon.tsh,v 1.1 2019/07/15 16:08:48 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 messages below though, string is      "
: "  in fact optional (for this script, but not for if(1)).  NOTE: For   "
: "  this script to be found & function correctly, 1) copy it to a       "
: "  directory on your PATH, ensuring the copied script is executable    "
: "  by your effective user/group id/name (see chown(8), chgrp(1), and   "
: "  chmod(1) if needed), and invoke it as in the 1st usage message; 2)  "
: "  or invoke it directly, as in the 2nd usage message (or similar).    "
:
: "  usage: ifzyon [string]                "
: "     or:                                "
: "  usage: tsh [path/to/]ifzyon [string]  "
:

:
: " There is no need to check for correct usage. "
:
: >>$0'' <'' ; : >>$1'' <''
: " Make temporary directory, or fail with an error & non-zero status. "
if ! { mkdir -m 0700 /tmp/ifzyon-$$ } if { exit } if A = B

( : ) >/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-$$/expr
tsh /tmp/ifzyon-$$/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

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