1 files changed, 5 insertions, 0 deletions
diff --git a/src/utilities.c b/src/utilities.c
index c8b08b9..e183d5f 100644
--- a/src/utilities.c
+++ b/src/utilities.c
@@ -158,6 +158,11 @@ char *parse_flags(int argc, char *argv[], pid_t *pid, bool *stdout_override, boo
                 fprintf(stderr, "Bad PID %s given, must be integer.\n", optarg);
                 exit(1);
             }
+            // check if the given `pid` is valid
+            if (getpgid(*pid) < 0) {
+                fprintf(stderr, "Bad PID %s given. PID is not valid or does not exist.\n", optarg);
+                exit(1);
+            }
             break;
         case 's':
             *stdout_override = true;