Shell: Make a new session at start if there's no active session

Author: https://github.com/alimpfard
Commit: a43d9c4fe0
Pull-request: https://github.com/SerenityOS/serenity/pull/3533
Issue: https://github.com/SerenityOS/serenity/issues/3530

Shell/Shell.cpp

@@ -733,8 +733,10 @@ RefPtr<Job> Shell::run_command(const AST::Command& command)
             perror("setpgid");
 
         if (!m_is_subshell) {
-            tcsetpgrp(STDOUT_FILENO, pgid);
-            tcsetpgrp(STDIN_FILENO, pgid);
+            if (tcsetpgrp(STDOUT_FILENO, pgid) != 0)
+                perror("tcsetpgrp(OUT)");
+            if (tcsetpgrp(STDIN_FILENO, pgid) != 0)
+                perror("tcsetpgrp(IN)");
         }
     }