added background job support.

main.c

@@ -6,17 +6,28 @@
 #include<readline/readline.h>
 #include<readline/history.h>
 #include<signal.h>
+pid_t backgroundPids[64];
+int backgroundCount = 0;
 void handleSIGINT(int sig) {
   printf("\n");
 }
-int detectBackgrount(char **args) {
+void handleSIGCHLD(int sig) {
+    int pid = waitpid(-1, NULL, WNOHANG);
+    for(int i = 0; i < backgroundCount; i++) {
+        if(backgroundPids[i] == pid) {
+            printf("\n[done] %d\n", pid);
+            backgroundPids[i] = 0;  // clear it
+        }
+    }
+}
+int detectBackground(char **args) {
   for (int i = 0; args[i] != NULL; i++) {
     if (strcmp(args[i], "&") == 0) {
       args[i] = NULL;
-      return 0;
+      return 1;
     }
     }
-  return 1;
+  return 0;
 }
 int seperatePipe(char **args) {
   for(int i = 0; args[i] != NULL; i++) {
@@ -78,6 +89,7 @@ char **parse(char *line) {
 }
 int main() {
 	signal(SIGINT, handleSIGINT);
+	signal(SIGCHLD, handleSIGCHLD);
 	while(1) {
 		char *user = getenv("USER");
 		char dir[1024];
@@ -92,7 +104,7 @@ int main() {
 		char **parsed = parse(line);
 		if(parsed[0] == NULL) { free(parsed); free(line); continue; }
 		if(handleBuiltins(parsed)) { free(line); free(parsed); continue; }
-		int background = detectBackgrount(parsed);
+		int background = detectBackground(parsed);
 		int pipeIndex = seperatePipe(parsed);
 		if (pipeIndex != -1) { 
 		  executePipe(parsed, pipeIndex);
@@ -102,12 +114,17 @@ int main() {
 		}
 		pid_t pid = fork();
 		if(pid == 0) {
+		  signal(SIGINT, SIG_DFL);
 		  if(execvp(parsed[0], parsed) == -1 ) {
 		    perror("tinysh");
 		    exit(1);
 		  }
-		} else if(pid > 0 && background != 0) {
-		  wait(NULL);
+		} else if(pid > 0) {
+		  if(background) { 
+		    printf("{background} %d \n", pid);
+		    backgroundPids[backgroundCount++] = pid;
+		  }
+		  else wait(NULL);
 		} 
 		free(parsed);
 		free(line);