show error why output log append failed

diff --git a/teeboth b/teeboth
index caf4620ae6296a4af41b65b80b3e4092221a198f..d5983527f35b78137fffde4b7dca69e1687bd5de 100755 (executable)
--- a/teeboth
+++ b/teeboth
@@ -11,7 +11,7 @@ use IO::Select;
 my $out = shift @ARGV;
 die unless @ARGV;
 
-open my $fout, ">>", $out or die if $out;
+open my $fout, ">>", $out or die "Can't write to $out: $!" if $out;
 
 my $select = IO::Select->new();
 my $alive = 1;