add ps command

src/emulator/commands/index.js

@@ -10,6 +10,7 @@ let cmds = {
     'export_file': require('./export_file'),
     'import_file': require('./import_file'),
     'zsh': require('./zsh'),
+    'ps': require('./ps'),
 
     // alias l='ls -l'
     'l': (a,t) => {require('./ls')([...a, '-l'], t)},

src/emulator/commands/ps.js

@@ -0,0 +1,20 @@
+const { Terminal } = require("xterm");
+
+/**
+ * 
+ * @param {string[]} argv 
+ * @param {Terminal} terminal 
+ */
+module.exports = (argv, terminal) => {
+    if (argv.indexOf('--help') != -1) {
+        terminal.write(
+`Usage: ${argv[0]} [OPTIONS]
+Show current process list`);
+        return;
+    }
+    terminal.write(
+`\tPID\tTTY\tTIME\tCMD
+ 42\tpts/0\t00:00:00\tzsh
+ 43\tpts/0\t00:00:00\tps
+`);
+}