sh: Build a more elaborate prompt using the system hostname and username

apps/sh.cpp

@@ -6,10 +6,12 @@
 #include <os/Process.h>
 
 #include <errno.h>
+#include <pwd.h>
 #include <stddef.h>
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
+#include <sys/utsname.h>
 #include <sys/wait.h>
 #include <unistd.h>
 
@@ -28,6 +30,12 @@ static Result<void> execute_command(StringView command)
     return os::Process::exec(args[0].view(), args.slice());
 }
 
+struct utsname g_sysinfo;
+
+const char* hostname = "";
+const char* username = "";
+char prompt_end = '$';
+
 Result<int> luna_main(int argc, char** argv)
 {
     StringView path;
@@ -55,12 +63,23 @@ Result<int> luna_main(int argc, char** argv)
         input_file->set_close_on_exec();
     }
 
+    if (interactive)
+    {
+        // Set up everything to form a prompt.
+        uname(&g_sysinfo);
+        hostname = g_sysinfo.nodename;
+
+        if (getuid() == 0) prompt_end = '#';
+        struct passwd* pw = getpwuid(getuid());
+        if (pw) { username = pw->pw_name; }
+    }
+
     while (1)
     {
         if (interactive)
         {
             auto cwd = TRY(os::FileSystem::working_directory());
-            printf("sh %s%c ", cwd.chars(), getuid() == 0 ? '#' : '$');
+            printf("%s@%s:%s%c ", username, hostname, cwd.chars(), prompt_end);
         }
 
         auto cmd = TRY(input_file->read_line());