* gash/commands/tr.scm: New file.
* gash/bournish-commands.scm: Use it.
* build-aux/build-guile.sh: Compile it.
* configure: Wrap it.
* .gitignore: Ignore it.
* gash/commands/mv.scm: New file.
* gash/bournish-commands.scm: Use it.
* build-aux/build-guile.sh: Compile it.
* configure: Wrap it.
* .gitignore: Ignore it.
* gash/commands/basename.scm: New file.
* build-aux/build-guile.sh: Compile it.
* configure: Create script.
* gash/bournish-commands.scm (basename-command): New variable.
(%bournish-commands): Add it.
* gash/commands/dirname.scm: New file.
* build-aux/build-guile.sh: Compile it.
* configure: Create script.
* gash/bournish-commands.scm (dirname-command): New variable.
(%bournish-commands): Add it.
* gash/commands/touch.scm: New file.
* build-aux/build-guile.sh: Compile it.
* configure: Create script.
* gash/bournish-commands.scm (touch-command): New variable.
(%bournish-commands): Add it.
* gash/commands/rmdir.scm: New file.
* build-aux/build-guile.sh: Compile it.
* configure: Create script.
* gash/bournish-commands.scm (rmdir-command): New variable.
(%bournish-commands): Add it.
* gash/shell-utils.scm (rmdir-p): New function.
* gash/commands/mkdir.scm: New file.
* build-aux/build-guile.sh: Compile it.
* configure: Create script.
* gash/bournish-commands.scm (mkdir-command): New variable.
(%bournish-commands): Add it.
* gash/commands/sed.scm: New file.
* build-aux/build-guile.sh: Compile it.
* configure: Create script.
* gash/shell-utils.scm (with-atomic-file-replacement,
substitute*): New function, Import from Guix.
(substitute-port): New function.