neovim, dotfiles-install: Added an auto-install routine to the bashrc.d that downloads vim-plug for now

.bashrc.d/dotfiles_install.bashrc

@@ -0,0 +1,64 @@
+# This is the first-run installation of the dotfiles utility. Although I have
+# been trying to avoid the need of executing additional code to put my config
+# files into place, that is not always possible or practical. The following
+# script is my attempt to make this as painless as possible.
+
+# Get the checksum of this very file.
+read -r checksum _ <<< $(sha256sum "${BASH_SOURCE[0]}")
+
+# Compare the computed checksum to a cached version from the environment. This
+# is done instead of a boolean token, so that the installation will run again
+# automatically, should this file change after an update.
+if [[ $checksum != $DOTFILES_INSTALL_CHECKSUM ]]; then
+
+  # If the checksum differed, source the file that contains the cached checksum
+  # and compare again to make sure that an update has not occured and already
+  # been processed since the environment has last been sourced at the beginning
+  # of the login session. Testing twice is a trade-off because most of the time
+  # the first test will fail and no file has to be sourced.
+  if [[ -r ~/.environment.d/dotfiles_install.env ]]; then
+     . ~/.environment.d/dotfiles_install.env
+  fi
+  if [[ $checksum != $DOTFILES_INSTALL_CHECKSUM ]]; then
+    # Installation starts here. Sections should still be designed in a way that
+    # they won't run twice if possible.
+    ############################################################################
+    echo "Dotfiles: Starting automatic installation routines"
+    dotfiles_install_error="no"
+
+
+    # vim-plug
+    if ! [[ -f ~/.local/share/nvim/site/autoload/plug.vim ]]; then
+      echo "Dotfiles: Downloading vim-plug..."
+      if curl \
+        --fail \
+	--location \
+	--retry 5 \
+	--retry-delay 1 \
+        --create-dirs \
+	--progress-bar \
+        --output ~/.local/share/nvim/site/autoload/plug.vim \
+        https://raw.githubusercontent.com/junegunn/vim-plug/master/plug.vim
+      then
+        echo "Dotfiles: Done"
+      else
+        echo "Dotfiles: Error downloading vim-plug"
+	dotfiles_install_error="yes"
+      fi
+    fi
+
+
+    ############################################################################
+    # Installation ends here. If we have come this far the installation should
+    # have been successful. Write the current checksum of this file to
+    # dotfiles_install.env and export the variable for good measure.
+    if [[ $dotfiles_install_error == "no" ]]; then
+      echo "Dotfiles: Automatic installation successful. Setting new checksum..."
+      echo "DOTFILES_INSTALL_CHECKSUM=$checksum" > ~/.environment.d/dotfiles_install.env
+      export DOTFILES_INSTALL_CHECKSUM=$checksum
+    else
+      echo "Dotfiles: Errors were encountered during automatic installation"
+      echo "Dotfiles: Installation can be re-run by opening a new shell"
+    fi
+  fi
+fi