1 files changed, 79 insertions, 0 deletions
diff --git a/bin/muffle b/bin/muffle
new file mode 100755
index 0000000..73c9103
--- /dev/null
+++ b/bin/muffle
@@ -0,0 +1,79 @@
+#!/bin/sh
+set -eu
+
+usage() {
+	cat <<-'EOF'
+		Usage:
+		  muffle [--] COMMAND...
+		  muffle -h
+	EOF
+}
+
+help() {
+	cat <<-'EOF'
+
+
+		Options:
+		  -h, --help    show this message
+
+		  COMMAND       the COMMAND to be muffled
+
+
+		Conditionally omit STDOUT and STDERR of COMMAND:
+		if command exits with an error, print its original output to the
+		corresponding streams, but when there is no error, throw the
+		output away, "muffling" the COMMAND.
+
+
+		Examples:
+
+		  Only print anything if the test fails:
+
+		    $ muffle sh tests/assert-makefile.sh
+	EOF
+}
+
+
+for flag in "$@"; do
+	case "$flag" in
+		(--)
+			break
+			;;
+		(--help)
+			usage
+			help
+			exit
+			;;
+		(*)
+			;;
+	esac
+done
+
+while getopts 'h' flag; do
+	case "$flag" in
+		(h)
+			usage
+			help
+			exit
+			;;
+		(*)
+			usage >&2
+			exit 2
+			;;
+	esac
+done
+shift $((OPTIND - 1))
+
+
+OUT="$(mkstemp)"
+ERR="$(mkstemp)"
+trap 'rm -f "$OUT" "$ERR"' EXIT
+
+STATUS=0
+"$@" 1>"$OUT" 2>"$ERR" || STATUS=$?
+
+if [ "$STATUS" != 0 ]; then
+	cat "$OUT"
+	cat "$ERR" >&2
+	exit "$STATUS"
+fi