* geesh/shell.scm (swap-and-shift-pairs): New function.
(make-pipes): New function.
(plumb): New function.
(sh:pipeline): New public function.
* tests/shell.scm: Test it.
Before, we were using raw file descriptors. This worked okay, but
there was interference caused by port buffering. Doing everything at
the port level avoids this problem, and has the added benefit of
allowing one to use the 'current-*-port' parameters with the shell
module (in a limited way, but there is room for improvement).
* geesh/shell.scm (*fd-count*): New variable.
(fd->current-port): New function.
(install-current-ports!): New function.
(exec-utility): Use it to set up file descriptors.
(save-and-install-redirect!): Rename this...
(save-and-set-redirect): ...to this and modify the current port
parameters instead of raw file descriptors.
(restore-saved-fdes!): Rename this...
(restore-saved-port): ...to this.
(sh:with-redirects): Adjust to use the renamed functions.
(sh:substitute-command): Parameterize the current ports directly
instead of using redirects.
* tests/shell.scm: Add tests to check if port buffers cause problems.
* geesh/shell.scm (%subshell): New function factored out from 'subshell'.
(subshell): Use it.
(substitute-command): New public function.
* tests/shell.scm: Test it.
* .dir-locals.el: Indent it nicely.
* geesh/shell.scm (save-and-install-redirect!): New function.
(restore-saved-fdes!): New function.
(with-redirects): New public function.
* tests/shell.scm: Test it.
* .dir-locals.el: Indent it nicely.
* geesh/built-ins/echo.scm: New file.
* geesh/built-ins.scm: New file.
* Makefile.scm: Add them.
* geesh/shell.scm (exec-let): Include built-ins in command search.
* tests/shell.scm: Add a test for this.
* geesh/shell.scm (slashless?) New function.
(split-search-path): New function.
(find-utility): New function.
(exec-let): Use them to search PATH for a utility when appropriate.
(exec): Update doc string.
* tests/shell.scm: Test it.
Timothy Sample