sets debugging flags. To watch how it executes your program, use
B<-Dtls>. (This works only if debugging is compiled into your
Perl.) Another nice value is B<-Dx>, which lists your compiled
-syntax tree. And B<-Dr> displays compiled regular expressions. As an
-alternative, specify a number instead of list of letters (e.g., B<-D14> is
-equivalent to B<-Dtls>):
+syntax tree. And B<-Dr> displays compiled regular expressions;
+the format of the output is explained in L<perldebguts>.
+
+As an alternative, specify a number instead of list of letters (e.g.,
+B<-D14> is equivalent to B<-Dtls>):
1 p Tokenizing and parsing
2 s Stack snapshots
as it executes, the way that C<sh -x> provides for shell scripts,
you can't use Perl's B<-D> switch. Instead do this
+ # If you have "env" utility
+ env=PERLDB_OPTS="NonStop=1 AutoTrace=1 frame=2" perl -dS program
+
# Bourne shell syntax
$ PERLDB_OPTS="NonStop=1 AutoTrace=1 frame=2" perl -dS program