Add EMBS remote access setup: embs.sh, README guide, VLAB docs

embs.sh

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+#!/usr/bin/env bash
+#
+# embs.sh - connect to the York CS Linux server with the Vivado / Vitis GUI
+#           forwarded to the XQuartz X server running on this Mac.
+#
+# Vivado and Vitis have no macOS build, so they run on csteach0.york.ac.uk and
+# their windows are drawn here by XQuartz over an X11-forwarded SSH connection.
+#
+# Usage:
+#   ./embs.sh                      interactive shell, X11 forwarded (normal use)
+#   ./embs.sh --check              verify the local X server and show what would run
+#   ./embs.sh 'vivado -version'    run one remote command, then disconnect
+#
+# The remote host can be overridden, e.g.  EMBS_HOST=csteach1.york.ac.uk ./embs.sh
+#
+# Note: this script only prepares the local X server and starts ssh. The hop
+# through the SSH gateway, and any 2FA prompt it raises, are handled by the
+# ProxyCommand already configured in ~/.ssh/config.
+
+set -e
+
+HOST="${EMBS_HOST:-csteach0.york.ac.uk}"
+XDPYINFO=/opt/X11/bin/xdpyinfo
+
+# Return the first local X display we can actually reach, or nothing.
+working_display() {
+    local d
+    for d in "${DISPLAY:-}" ":0"; do
+        [ -n "$d" ] || continue
+        if [ -x "$XDPYINFO" ] && "$XDPYINFO" -display "$d" >/dev/null 2>&1; then
+            printf '%s' "$d"
+            return 0
+        fi
+    done
+    return 1
+}
+
+start_xquartz() {
+    if [ ! -d /Applications/Utilities/XQuartz.app ]; then
+        echo "error: XQuartz is not installed." >&2
+        echo "       Install it with:  brew install --cask xquartz" >&2
+        return 1
+    fi
+    echo "Starting XQuartz..."
+    open -a XQuartz || return 1
+    local i
+    for i in $(seq 1 30); do
+        if "$XDPYINFO" -display :0 >/dev/null 2>&1; then
+            return 0
+        fi
+        sleep 0.5
+    done
+    return 1
+}
+
+CHECK_ONLY=no
+if [ "${1:-}" = "--check" ]; then
+    CHECK_ONLY=yes
+    shift
+fi
+
+# --- 1. Make sure there is a usable local X server ---------------------------
+DISP="$(working_display || true)"
+if [ -z "$DISP" ] && [ "$CHECK_ONLY" = no ]; then
+    if start_xquartz; then
+        DISP=":0"
+    fi
+fi
+
+if [ -z "$DISP" ]; then
+    echo "warning: no X server reachable on this Mac." >&2
+    echo "         XQuartz is installed but may not be running, or DISPLAY is not exported." >&2
+    echo "         Try:  open -a XQuartz   (then log out and back in once)" >&2
+    echo "         Vivado / Vitis windows will NOT appear until this is fixed." >&2
+else
+    export DISPLAY="$DISP"
+fi
+
+# --- 2. Report and connect ---------------------------------------------------
+if [ "$CHECK_ONLY" = yes ]; then
+    echo "XQuartz installed : yes"
+    echo "X server reachable: ${DISP:-no}"
+    echo "DISPLAY would be  : ${DISP:-<unset>}"
+    echo "Would run         : ssh -Y -C -o ServerAliveInterval=60 $HOST"
+    if [ "$#" -gt 0 ]; then
+        echo "Remote command    : $*"
+    fi
+    exit 0
+fi
+
+echo "Connecting to $HOST with DISPLAY=${DISPLAY:-<unset>} ..."
+echo "If the gateway asks for a password or Duo approval, that is the university's 2FA."
+echo
+
+if [ "$#" -gt 0 ]; then
+    exec ssh -Y -C -o ServerAliveInterval=60 "$HOST" "$@"
+else
+    exec ssh -Y -C -o ServerAliveInterval=60 "$HOST"
+fi