Allow input from redirected stdin

chatgpt.sh

@@ -216,15 +216,16 @@ fi
 
 running=true
 # check input source
-# if prompt already entered, run on pipe mode (run once, no chat)
-# prompt from pipe
-if [ -p /dev/stdin ]; then
-	pipe_mode_prompt+=$(cat -)
 # prompt from argument
-elif [ -n "$prompt" ]; then
+if [ -n "$prompt" ]; then
 	pipe_mode_prompt=${prompt}
-else
+# if input file_descriptor is a terminal
+elif [ -t 0 ]; then
 	echo -e "Welcome to chatgpt. You can quit with '\033[36mexit\033[0m'."
+# if prompt already entered, run on pipe mode (run once, no chat)
+# prompt from pipe
+else
+	pipe_mode_prompt+=$(cat -)
 fi
 
 while $running; do