From d43848f7225850d8a1ac197b699dcb40b0fdf955 Mon Sep 17 00:00:00 2001
From: cyp0633 <cyp0633@cyp0633.icu>
Date: Wed, 25 May 2022 12:32:33 +0800
Subject: [PATCH] Shell Lab: trace07

---
 shlab/tsh.c | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/shlab/tsh.c b/shlab/tsh.c
index 0ef2bc6..c9d8f90 100644
--- a/shlab/tsh.c
+++ b/shlab/tsh.c
@@ -347,9 +347,12 @@ void sigchld_handler(int sig)
 void sigint_handler(int sig)
 {
     pid_t pid = fgpid(jobs);    // get pid of foreground job
-    if (kill(-pid, SIGINT) < 0) // try to send SIGINT
+    if (pid != 0) // if no foreground job (PID=0), do nothing (ONLY send to foreground)
     {
-        unix_error("sigint error"); // failed
+        if (kill(-pid, SIGINT) < 0) // try to send SIGINT
+        {
+            unix_error("sigint error"); // failed
+        }
     }
     return;
 }