add bad link check

fixes #54

Author: vladak

.github/workflows/compile.yml

@@ -24,7 +24,7 @@ jobs:
       uses: actions/checkout@v4
       with:
         repository: devnull-cz/unix-linux-prog-in-c-src
-        path: src
+        path: unix-linux-prog-in-c-src
     - name: Install pre-requisites for LaTeX
       working-directory: master
       run: ./dev/install-latex.sh
@@ -40,3 +40,6 @@ jobs:
     - name: Compile
       working-directory: master
       run: make slides notes
+    - name: Check example links
+      working-directory: master
+      run: ./dev/check-examples.sh

dev/check-examples.sh

@@ -0,0 +1,20 @@
+#!/bin/bash
+#
+# Verify the \example{} are all valid links to the source repository.
+#
+# Assumes the source repository is checked about to the '../unix-linux-prog-in-c-src' directory
+# and also that the TeX documents were already processed by m4.
+#
+# Lastly, it assumes that the \example{} does not span multiple lines.
+#
+
+for m4file in *.m4.tex; do
+	echo "### $m4file"
+	cat "$m4file" | grep -o '\\example{[[:alnum:]\/\._\-]\+}' | \
+	    sort -u | sed -e 's/^\\example{//' -e 's/}$//' | while read example; do
+		if [[ ! -f ../unix-linux-prog-in-c-src/$example ]]; then
+			echo "example $example is bad link"
+			exit 1
+		fi
+	done
+done