diff --git a/sh/functions.sh b/sh/functions.sh
index 99c83989..2be38a65 100644
--- a/sh/functions.sh
+++ b/sh/functions.sh
@@ -101,6 +101,24 @@ uniqify() {
     echo "${result# *}"
 }
 
+yesno()
+{
+	[ -z "$1" ] && return 1
+
+	case "$1" in
+		[Yy][Ee][Ss]|[Tt][Rr][Uu][Ee]|[Oo][Nn]|1) return 0;;
+		[Nn][Oo]|[Ff][Aa][Ll][Ss][Ee]|[Oo][Ff][Ff]|0) return 1;;
+	esac
+
+	local value=
+	eval value=\$${1}
+	case "${value}" in
+		[Yy][Ee][Ss]|[Tt][Rr][Uu][Ee]|[Oo][Nn]|1) return 0;;
+		[Nn][Oo]|[Ff][Aa][Ll][Ss][Ee]|[Oo][Ff][Ff]|0) return 1;;
+		*) vewarn "\$${1} is not set properly"; return 1;;
+	esac
+}
+
 KV_to_int() {
 	[ -z $1 ] && return 1