util: watch-entropy

1 files changed, 19 insertions, 0 deletions

diff --git a/src/watch-entropy b/src/watch-entropy
new file mode 100755
index 0000000..e0f3261
--- /dev/null
+++ b/src/watch-entropy
@@ -0,0 +1,19 @@
+#!/usr/bin/perl
+$SIG{INT} = sub { ++$interrupted; };
+use Time::HiRes qw(sleep);
+use constant default_file => "/proc/sys/kernel/random/entropy_avail";
+use constant default_format => 'system entropy: %-5d bits';
+$|++;
+my $file = shift || default_file;
+my $format = $file eq default_file ? default_format : "$file: %s";
+my $sleep_time = shift || 0.2;
+open ENT, "<", $file or die "$0: error opening $file: $!\n";
+my $last; while (<ENT>) {
+  chomp;
+  printf "
$format", $_ . (" " x (length($last) - length $_)) unless $_ eq $last;
+  $last = $_;
+  last if $interrupted;
+  sleep $sleep_time;
+  seek ENT, 0, 0;
+}
+print "\n";