* gash/shell.scm (swap-and-shift-pairs): Remove procedure.
(make-pipes): Remove procedure.
(plumb): Accept another port as an argument and close it when setting
up the child process.
(sh:pipeline): Do not use 'make-pipes' to create all the pipe ports
upfront, but rather create them as needed and give them directly to
'plumb'.
* gash/shell.scm (redir->parameter+port): Rename this...
(process-redirect): ...to this, and make it return a list with the
third element being a boolean indicating if the port was opened by us.
(sh:with-redirects): Close ports when the new boolean is set.
* gash/shell.scm (sh:exec-let): Do not throw on special built-in
errors.
* gash/built-ins/break.scm (main),
gash/built-ins/continue.scm (main),
gash/built-ins/return.scm (main),
gash/built-ins/shift.scm (main): Throw on error.
* gash/environment.scm (save-variables-excursion): New procedure.
* gash/shell.scm (sh:exec-let): Use it to set up temporary assignments
during the extent of a function.
* tests/temporary-assignments.org: New file.
* Makefile.am (TESTS): Add it.
It turns out that 'with-continuation-barrier' allows delimited
continuations (i.e., prompts) to get through.
* gash/shell.scm (%subshell): Replace 'with-continuation-barrier' with
'dynamic-wind', making sure to preserve exit statuses that were leaked
through before.
* tests/unit/shell.scm (call-with-temporary-directory): Replace
'with-continuation-barrier' with 'dynamic-wind'.
* tests/spec/oil.scm: Enable previously failing tests.
* gash/built-ins/utils.scm (string->positive-integer): New function.
* gash/built-ins/break.scm (main): Use it to simplify argument
checking; check for too many arguments; and print messages on errors.
* gash/built-ins/continue.scm (main): Ditto.
* gash/shell.scm (sh:exec-let): Throw an error if a special built-in
fails.
* tests/spec/oil.scm: Enable and adjust previously failing tests.
* configure.ac (GUILE_PKG): Add 2.0.
* gash/textual-ports.scm: New file.
* Makefile.am: Add it.
* gash/lexer.scm, gash/parser.scm, gash/shell.scm: Use it in place of
'(ice-9 textual-ports)'.
* tests/unit/shell.scm: Use it in place of '(ice-9 textual-ports)';
replace '(ice-9 textual-ports)' with '(rnrs io ports)' in sub-scripts;
and add a shim for 'setvbuf'.
gash/environment.scm: Remove file.
geesh/*: Move these files into the 'gash' folder and replace all
instances of the word 'geesh'.
scripts/geesh.in: Remove file.
HACKING, INSTALL, Makefile.am, configure.ac, guix.scm,
tests/bootstrap/bash-without-bash.scm, tests/spec/Makefile.am,
tests/spec/check-spec, tests/spec/oil.scm, tests/unit/*,
tools/coverage.in: Replace all instances of the word 'geesh'.
Co-authored-by: Jan Nieuwenhuizen <janneke@gnu.org>