Wait till the system is idle for $1 minutes.

diff --git a/bin/idle b/bin/idle
new file mode 100755 (executable)
index 0000000..97863e4
--- /dev/null
+++ b/bin/idle
@@ -0,0 +1,79 @@
+#! /usr/bin/perl
+#
+# $Id$
+
+use strict;
+use warnings;
+
+my $idle_want=$ARGV[0] || 30;
+die if @ARGV>1 || $idle_want!~/^\d+$/;
+$idle_want*=60;
+
+use User::Utmp;
+
+# Users respected for the 'idle' state (see $IdleMax):
+my @ValidUsers=qw(root lace jkratoch);
+
+sub useridle()
+{
+       my %valid_users=map(($_=>1),@ValidUsers);
+       my($idlebest,$linebest);
+       for my $utmp (User::Utmp::getut()) {
+               local $_;
+               next if defined($_=$utmp->{"ut_type"}) && $_!=&User::Utmp::USER_PROCESS();
+               next if defined($_=$utmp->{"ut_user"}) && !$valid_users{$_};
+               my $line="/dev/".$utmp->{"ut_line"};
+               my $atime=(stat $line)[8];
+               my $what="user \"".($utmp->{"ut_user"} || "<local>")."\", line \"$line\"";
+               warn "Unable to stat $what" and next if !$atime;
+               my $idle=time()-$atime;
+               warn "atime in future for $what" and next if $idle<0;
+               next if defined $idlebest && $idlebest<=$idle;
+               $idlebest=$idle;
+               $linebest=$line;
+               }
+       return !wantarray() ? $idlebest : ($idlebest,$linebest);
+}
+
+sub mplayer_running()
+{
+       local *F;
+       open F,"/proc/net/unix" or die;
+       my %unix;
+       <F>;
+       local $_;
+       while (<F>) {
+               /^(?:\S+\s+){6}(\d+)\s/ or die;
+               $unix{$1}=1;
+               }
+       close F or die;
+
+       local $_;
+       while (</proc/*/exe>) {
+               (my $fdname=$_)=~s{/exe$}{/fd};
+               $_=readlink or next;
+               m{/mplayer$} or next;
+               while (<$fdname/*>) {
+                       $_=readlink or next;
+                       my $inode=/^\Qsocket:[\E(\d+)\Q]\E$/ or next;
+                       return 1 if $unix{$1};
+                       }
+               }
+       return;
+}
+
+$|=1;
+for (;;) {
+       my $idle_is=useridle();
+       if ($idle_is>=$idle_want) {
+               if (!mplayer_running()) {
+                       print "\n";
+                       exit 0;
+               }
+               print "M";
+               sleep 10;
+       } else {
+               print ".";
+               sleep $idle_want-$idle_is;
+       }
+}