From 3b56275ef64c8c9b8cf407abd663f4bb027c520c Mon Sep 17 00:00:00 2001
From: Eric Anders <eric@stuckshut.com>
Date: Thu, 4 Aug 2016 15:51:15 -0500
Subject: [PATCH] Check for empty or whitespace PROMPT_COMMAND before appending
 preexec_invoke_cmd

---
 lib/preexec.bash | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/lib/preexec.bash b/lib/preexec.bash
index b1662a93..87922946 100644
--- a/lib/preexec.bash
+++ b/lib/preexec.bash
@@ -122,7 +122,11 @@ function preexec_install () {
     shopt -s extdebug > /dev/null 2>&1
 
     # Finally, install the actual traps.
-    PROMPT_COMMAND="${PROMPT_COMMAND};preexec_invoke_cmd"
+    if [[ ! -z "${PROMPT_COMMAND// }" ]]; then
+      PROMPT_COMMAND="${PROMPT_COMMAND};preexec_invoke_cmd"
+    else
+      PROMPT_COMMAND="preexec_invoke_cmd"
+    fi
     trap 'preexec_invoke_exec' DEBUG
 }