From ccee8c418ead4b58e4b099d99d230c3ab1b93413 Mon Sep 17 00:00:00 2001
From: Evgeny Zinoviev <me@ch1p.io>
Date: Sun, 19 Sep 2021 03:38:26 +0300
Subject: add some safety checks

---
 write-intel-brightness | 29 ++++++++++++++++++++++++++++-
 1 file changed, 28 insertions(+), 1 deletion(-)

(limited to 'write-intel-brightness')

diff --git a/write-intel-brightness b/write-intel-brightness
index 5960144..fe12b5d 100755
--- a/write-intel-brightness
+++ b/write-intel-brightness
@@ -1,9 +1,36 @@
 #!/bin/bash
 
+PROGNAME="$0"
+
 echoerr() {
-    >&2 echo "$@"
+    >&2 echo "error: $@"
+}
+
+die() {
+	echoerr "$@"
+	exit 1
+}
+
+usage() {
+	cat <<-_EOF
+	Usage: $PROGNAME +|-
+	_EOF
+	exit
 }
 
+command_exists() {
+	command -V "$1" >/dev/null 2>&1
+}
+
+[ -z "$1" ] && usage
+[ "$EUID" != 0 ] && die "must be run as root"
+
+for c in intel_reg awk; do
+	if ! command_exists $c; then
+		die "$c not found"
+	fi
+done
+
 max=$(intel_reg read 0xC8254 2>/dev/null | awk '{print $3}')
 max=${max:2:4}
 max_dec=$(printf "%d" $((16#$max)))
-- 
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