From d5ee29f3da9dd09278ebea7464e21fae40911130 Mon Sep 17 00:00:00 2001
From: Paul Buetow <paul@buetow.org>
Date: Sat, 30 Jul 2022 11:21:06 +0100
Subject: automatically check whether date, grep and sed are GNU or not

---
 gemtexter | 11 +++++++++++
 1 file changed, 11 insertions(+)

diff --git a/gemtexter b/gemtexter
index ffd128f..3d03189 100755
--- a/gemtexter
+++ b/gemtexter
@@ -49,6 +49,16 @@ Example:
 HELPHERE
 }
 
+# Make sure that there are the correct versions of the dependencies installed.
+ensure_gnu () {
+    for tool in $DATE $SED $GREP; do
+        if ! $tool --version | grep -q GNU; then
+            log ERROR "ERROR, \"$tool\" command is not the GNU version, please install!"
+            exit 2
+        fi
+    done
+}
+
 setup () {
     if [ ! -d "$CONTENT_BASE_DIR" ]; then
         cat <<END
@@ -74,6 +84,7 @@ END
 main () {
     local -r arg="$1"; shift
 
+    ensure_gnu
     setup
 
     case $arg in
-- 
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