add perl os

study_perl/simple-os/main.pl

@@ -0,0 +1,33 @@
+#!/usr/bin/perl
+use strict;
+use warnings;
+
+sub main {
+    print "Simple OS Simulator\n";
+    print "Type 'help' for available commands.\n";
+
+    while (1) {
+        print "> ";
+        chomp(my $input = <STDIN>);
+        
+        if ($input eq 'exit') {
+            last;
+        } elsif ($input eq 'help') {
+            print "Available commands:\n";
+            print "  help - show this help message\n";
+            print "  date - show the current date and time\n";
+           print "  echo <message> - print the given message\n";
+            print "  exit - exit the simulator\n";
+        } elsif ($input =~ /^echo (.*)$/) {
+            print "$1\n";
+        } elsif ($input eq 'date') {
+            my ($sec, $min, $hour, $mday, $mon, $year, $wday, $yday, $isdst) = localtime();
+            $year += 1900; $mon += 1;
+            print "$mon/$mday/$year $hour:$min:$sec\n";
+        } else {
+            print "Unknown command. Type 'help' for available commands.\n";
+        }
+    }
+}
+
+main();