all tasks

Task/Short-circuit-evaluation/UNIX-Shell/short-circuit-evaluation-1.sh

@@ -0,0 +1,19 @@
+a() {
+	echo "Called a $1"
+	"$1"
+}
+
+b() {
+	echo "Called b $1"
+	"$1"
+}
+
+for i in false true; do
+	for j in false true; do
+		a $i && b $j && x=true || x=false
+		echo "  $i && $j is $x"
+
+		a $i || b $j && y=true || y=false
+		echo "  $i || $j is $y"
+	done
+done

Task/Short-circuit-evaluation/UNIX-Shell/short-circuit-evaluation-2.sh

@@ -0,0 +1,12 @@
+alias a eval \''echo "Called a \!:1"; "\!:1"'\'
+alias b eval \''echo "Called b \!:1"; "\!:1"'\'
+
+foreach i (false true)
+	foreach j (false true)
+		a $i && b $j && set x=true || set x=false
+		echo "  $i && $j is $x"
+
+		a $i || b $j && set x=true || set x=false
+		echo "  $i || $j is $x"
+	end
+end

Task/Short-circuit-evaluation/UNIX-Shell/short-circuit-evaluation-3.sh

@@ -0,0 +1,8 @@
+# Succeeds, only prints "ok".
+if ( 1 || { echo This command never runs. } ) echo ok
+
+# Fails, aborts shell with "bad: Undefined variable".
+if ( 1 || $bad ) echo ok
+
+# Prints "error", then "ok".
+if ( 1 || `echo error >/dev/stderr` ) echo ok