From fea2fc7600315163eb20ff39845e12b23bdadd65 Mon Sep 17 00:00:00 2001
From: EuAndreh <eu@euandre.org>
Date: Sat, 1 Apr 2023 10:38:26 -0300
Subject: aux/lib.sh: Add generic assert_arg()

---
 aux/lib.sh | 12 +++++++++---
 1 file changed, 9 insertions(+), 3 deletions(-)

(limited to 'aux/lib.sh')

diff --git a/aux/lib.sh b/aux/lib.sh
index 52f1315..e345bd6 100644
--- a/aux/lib.sh
+++ b/aux/lib.sh
@@ -1,8 +1,14 @@
 #!/bin/sh
 
-#
-# Generally, utilities that I expected to exist in POSIX, but don't.
-#
+assert_arg() {
+	if [ -z "$1" ]; then
+		printf 'Missing %s.\n\n' "$2" >&2
+		cat <<-'EOF'
+			usage >&2
+			exit 2
+		EOF
+	fi
+}
 
 uuid() {
 	od -xN20 /dev/urandom |
-- 
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