Introduce a script to send G-code files on a Macintosh.

This is sender-mac.sh. See the top of this file for a description
on how to use it.

sender-mac.sh

@@ -0,0 +1,113 @@
+#!/bin/bash
+
+# This is a script to send G-code from Mac OS X. The problem with Mac OS X is,
+# stty settings on serial ports don't "stick", so it's impossible to set
+# e.g. the baud rate before connecting to that port. The solution is to use
+# a tool which can do both, setting the baud rate and sending characters.
+#
+# The tool of choice is the somewhat confusing "screen", part of the
+# standard Mac OS X distribution.
+#
+# --- Usage ---
+#
+# A nice feature of screen is, you can "detach" a connection which means,
+# you close the interactive part of screen, but the connection on the serial
+# is kept open. This allows so send multiple files to the controller without
+# triggering an auto-reset in between. You can do a full close as well, of
+# course.
+#
+# Start sending commands manually or re-attach to an earlier session:
+#
+#     ./sender-mac.sh
+#
+# Send a file:
+#
+#     ./sender-mac.sh <G-code file>
+#
+# Send multiple files:
+#
+#     ./sender-mac.sh <G-code file 1>
+#     ctrl-a d
+#     ./sender-mac.sh <G-code file 2>
+#
+# The tricky part with screen is to leave such an interactive session. Screen
+# doesn't react to the usual ctrl-c, but asks for ctrl-a. Following that ctrl-a
+# you can type single-character commands, like d (detach) or k (kill). There
+# is no visual feedback on hitting ctrl-a, type the command character blindly.
+#
+# Leave the session, keep the connection alive:
+#
+#     ctrl-a d
+#
+# Leave the session, drop the connection:
+#
+#     ctrl-a k y
+#
+# Stop sending the current file immediately:
+#
+#     ctrl-a k y
+#
+# After the file is sent, you're always dropped into interactive mode, so you
+# can send additional commands and/or leave the session.
+
+
+DEV=$(echo /dev/tty.usbserial*)
+BAUD=115200
+
+if [ "${STY}" = "" ]; then
+  # we're not inside a screen session, so
+  # create one and restart our selfs
+
+  # make sure we have a session
+  screen -r teacup -X detach >/dev/null
+  if [ $? -ne 0 ]; then
+    # creating in detached mode prevents -X exec later, unfortunately
+    (sleep 3 && screen -S teacup -d) &  ## hack alarm!
+    screen -S teacup $DEV $BAUD
+  fi
+
+  screen -S teacup -X clear
+  screen -S teacup -X exec '!!.' "$PWD"/$(basename $0) "$1"
+  screen -r teacup
+else
+  # we're called from inside screen,
+  # with the RepRap controller on stdin/stdout
+
+  # get an initial prompt
+  OK=""
+  echo
+  while true; do
+    read -t 10 OK MESSAGE
+    if [ "$OK" = "ok" ]; then break; fi
+    echo  # trigger a new "ok"
+  done
+
+  if [ -r "$1" ]; then
+    # send line by line and wait for "ok" each time
+    exec 3<> "$1"
+    while read <&3 LINE; do
+      echo -n "$LINE" >&2
+      echo $LINE
+      OK=""
+      while true; do
+        read OK MESSAGE
+        if [ $? -ne 0 ]; then
+          # probably a disconnection from screen
+          exit
+        fi
+        echo "<$OK>" >&2
+        if [ "$OK" = "ok" ]; then
+          break
+        fi
+      done
+      if [ "$MESSAGE" != "" ]; then
+        echo "$MESSAGE" >&2
+        sleep 1
+      fi
+    done
+    echo "File done, dropping to manual operation." >&2
+  else
+    echo "No readable file, proceed manually." >&2
+  fi
+fi
+