diff --git a/tsh.c b/tsh.c
index 8166269..157cfb4 100644
--- a/tsh.c
+++ b/tsh.c
@@ -168,23 +168,31 @@ void eval(char *cmdline)
   char *argv[MAXARGS]; // Save flags for process
   int bg = parseline(cmdline, argv); // See whether cmd is back or foreground and parse cmdline
   struct job_t *job;
+ 
+  sigset_t mask, prev_mask;
+  sigfillset(&mask);
+  sigprocmask(SIG_BLOCK, &mask, &prev_mask);
 
   if (argv[0] != NULL) { // Do nothing, but don't crash on empty line
     if (!builtin_cmd(argv)) { // if cmdline is not a builtin
-      int pid = fork(); // fork process
+     int pid = fork(); // fork process
       if (pid == 0) { // Child Process
+
+        setpgid(getpid(), 0);
+        sigprocmask(SIG_SETMASK, &prev_mask, NULL);
+
         if (execve(argv[0], argv, environ) != 0) { // if exec failed
           printf("%s Command not found.\n", argv[0]);
           exit(1);
         }
       } else { // Parent Process
-        wait(NULL);
         addjob(jobs, pid, bg ? BG : FG, cmdline);
+        sigprocmask(SIG_SETMASK, &prev_mask, NULL);
         if (bg) {
           job = getjobpid(jobs, pid);
           printf("[%d] (%d) %s", job->jid, pid, cmdline);
         } else {
-          // waitfg(pid);
+          waitfg(pid);
         }
       }
     }
@@ -272,26 +280,55 @@ int builtin_cmd(char **argv)
  */
 void do_bgfg(char **argv) 
 {
-  // struct job_t* job;
-  // if (argv[1][0] == '%') { // if job is chosing via jid
-  //   printf("jid: %s", &argv[1][1]);
-  //   job = getjobjid(jobs, atoi(&argv[1][1]));
-  // } else { // if job is chosing via pid
-  //   printf("pid: %s", argv[1]);
-  //   job = getjobpid(jobs, atoi(argv[1]));
-  // }
-
-  // if (job != NULL) {
-  //   if (!strcmp(argv[0], "bg")) { // Do this if bg
-  //     if (job->state == ST) {
-  //       job->state = BG;
-  //     }
-  //   } else { // Do this if fg
-  //     if (job->state == ST || job->state == BG) {
-  //       job->state = FG;
-  //     }
-  //   }
-  // }
+  struct job_t *job_1;
+  char *j = argv[1];
+  int JID;
+  pid_t PID;
+                
+  if(j==NULL){ // if no arg
+    fprintf(stderr,"%s command requires PID or %%jobid argument\n",argv[0]);
+    return;
+  }
+   
+  
+  else if(j[0] == '%'){ // case1 job id , ex) %5
+    JID = atoi(&j[1]);
+    if(!JID){
+      printf("%s: argument must be a PID or %%jobid\n", argv[0]);
+      return;
+    }
+    job_1 = getjobjid(jobs, JID);
+    if(job_1 == NULL){ // if not existing job
+      printf("%s no such job\n", argv[1]);
+      return;
+    }
+  }
+  else{ // case2 process id, ex) 5
+    PID = atoi(j);
+    if(!PID){
+      printf("%s: argument must be a PID or %%jobid\n", argv[0]);
+      return;
+    }
+    job_1 = getjobpid(jobs, PID);
+    if(job_1 == NULL){ // if non existant proc
+      printf("(%s) no such process\n", argv[1]);
+      return;
+    }
+  }
+        
+  PID = job_1->pid;
+        
+  if(!strcmp("bg", argv[0])){ //background job
+    job_1->state = BG;
+    printf("[%d] (%d) %s", job_1->jid, job_1->pid, job_1->cmdline);
+    kill(-PID, SIGCONT);
+                
+  }
+  else{ //foreground job
+    job_1->state = FG;
+    kill(-PID, SIGCONT);
+    waitfg(job_1->pid);
+  }
   return;
 }
 
@@ -319,8 +356,34 @@ void waitfg(pid_t pid)
  */
 void sigchld_handler(int sig) 
 {
-  deletejob(jobs, fgpid(jobs));
-  return;
+  int tmp_errno = errno;
+  sigset_t mask, prev_mask;
+  int child_status;
+  pid_t wpid;
+  sigfillset(&mask);
+
+  while ((wpid = waitpid(-1, &child_status, WNOHANG | WUNTRACED)) > 1) {
+    if (wpid < 0) {
+      unix_error("waitpid error");
+      return;
+    }
+    sigprocmask(SIG_BLOCK, &mask, &prev_mask);
+    struct job_t *job = getjobpid(jobs, wpid);
+
+    if (WIFSTOPPED(child_status)) {
+      printf("Job [%d] (%d) stopped by signal %d\n", job->jid, jobs->pid, SIGTSTP);
+      job->state = ST;
+    } else if (WIFEXITED(child_status)) {
+      deletejob(jobs, wpid);
+    } else if (WIFSIGNALED(child_status)) {
+      printf("Job [%d] (%d) terminated by signal %d\n", job->jid, jobs->pid, SIGINT);
+      deletejob(jobs, wpid);
+    }
+
+    sigprocmask(SIG_SETMASK, &prev_mask, NULL);
+  }
+
+  errno = tmp_errno;
 }
 
 /* 
@@ -330,6 +393,15 @@ void sigchld_handler(int sig)
  */
 void sigint_handler(int sig) 
 {
+  int tmp_errno = errno;
+  pid_t fg_pid = fgpid(jobs);
+
+  if (fg_pid) {
+    kill(-fg_pid, SIGINT);
+  }
+
+  errno = tmp_errno;
+
   return;
 }
 
@@ -340,6 +412,18 @@ void sigint_handler(int sig)
  */
 void sigtstp_handler(int sig) 
 {
+  int tmp_errno = errno;
+  sigset_t mask, prev_mask;
+
+  sigfillset(&mask);
+  sigprocmask(SIG_BLOCK, &mask, &prev_mask);
+
+  pid_t fg_pid = fgpid(jobs);
+
+  kill(-fg_pid, SIGTSTP);
+
+  sigprocmask(SIG_SETMASK, &prev_mask, NULL);
+  errno = tmp_errno;
   return;
 }