[augeas-devel] Add --interactive, -i option to run an interactive shell after evaluating STDIN and inputfile

[Raphael Pinson]

This patch adds a new --interactive,-i option to augtool.
This option allows to run an interactive shell after evaluating STDIN
or inputfile (given with --file,-f) when passed.

Example of use cases:

 * Bob would like to use augtool interatively to test /etc/fstab only.
   He sets up a setup.augtool file with the following:

     set /augeas/load/Fstab/lens fstab.lns
     set /augeas/load/Fstab/incl /etc/fstab
     load

  then runs `augtool --noautoload -if setup.augtool' and
  ends up in an interactive augtool session with his presets.


 * Alice wants to use augtool as a shell for some users,
   but she would like to restrict the default tree.


I've been thinking of playing with named pipes as well to keep an augtool
session open with a shell, but I can't figure out really how to deal with
that yet.