I have been having problems with string searches. I learned from a Perl Monks user that /m or /s were to be replacements for the deprecated "$*" which I am encountering in some old code that I didn't write, but need to modify to a newer system (using perl 5.14.2).

The script I am editing has the statement "$* = 0;". $* is never used again in the script. I read elsewhere that if I commented that statement out in the perl versions where it was deprecated, nothing would happen. I don't feel sure about that.

The docs were not very satisfying, so I decided to play around with various situations regarding pattern matching using /m, /s or just plain / to see what happens. Here is a script I wrote:

#! /usr/bin/perl -w

$re=qr/foo$/;
print $re; print "\n";
print "foo\\nbar\\n =~ \/$re\/s \t";
print "foo\nbar\n" =~ /$re/s ?"true":"false"; print "\n";
print "foo\\nbar\\n =~ \/$re\/m \t";
print "foo\nbar\n" =~ /$re/m ?"true":"false"; print "\n";
#
print "fred\\nfoo\\nbar\\n =~ \/$re\/s \t";
print "fred\nfoo\nbar\n" =~ /$re/s ?"true":"false"; print "\n";
print "fred\\nfoo\\nbar\\n =~ \/$re\/m \t";
print "fred\nfoo\nbar\n" =~ /$re/m ?"true":"false"; print "\n";
#
print "foo =~ \/$re\/s \t";
print "foo" =~ /$re/s ?"true":"false"; print "\n";
print "foo =~ \/$re\/m \t";
print "foo" =~ /$re/m ?"true":"false"; print "\n";
print "\\nfoo =~ \/$re\/s \t";
print "\nfoo" =~ /$re/s ?"true":"false"; print "\n";
print "\\nfoo =~ \/$re\/m \t";
print "\nfoo" =~ /$re/m ?"true":"false"; print "\n";
print "foobar =~ \/$re\/s \t";
print "foobar" =~ /$re/s ?"true":"false"; print "\n";
print "foobar =~ \/$re\/m \t";
print "foobar" =~ /$re/m ?"true":"false"; print "\n";
print "bar\\nfoo\\n =~ \/$re\/s \t";
print "bar\nfoo\n" =~ /$re/s ?"true":"false"; print "\n";
print "bar\\nfoo =~ \/$re\/m \t";
print "bar\nfoo" =~ /$re/m ?"true":"false"; print "\n";
print "bar\\nfoo\\n =~ \/$re\/ \t";
print "bar\nfoo\n" =~ /$re/ ?"true":"false"; print "\n";
print "foo\\nbar\\n =~ \/$re\/ \t";
print "foo\nbar\n" =~ /$re/ ?"true":"false"; print "\n";
print "fred\\nfoo\\nbar\\n =~ \/$re\/ \t";
print "fred\nfoo\nbar\n" =~ /$re/ ?"true":"false"; print "\n";
print "fred\\nfoo\\nbar\\n =~ \/$re\/ \t";
print "fred\nfoo\nbar\n" =~ /$re/ ?"true":"false"; print "\n";
print "foo =~ \/$re\/ \t";
print "foo" =~ /$re/ ?"true":"false"; print "\n";
print "foobar =~ \/$re\/ \t";
print "foobar" =~ /$re/ ?"true":"false"; print "\n";
print "\\nfoo =~ \/$re\/ \t";
print "\nfoo" =~ /$re/ ?"true":"false"; print "\n";
[download]

(?^:foo$)
foo\nbar\n =~ /(?^:foo$)/s      false
foo\nbar\n =~ /(?^:foo$)/m      false
fred\nfoo\nbar\n =~ /(?^:foo$)/s        false
fred\nfoo\nbar\n =~ /(?^:foo$)/m        false
foo =~ /(?^:foo$)/s     true
foo =~ /(?^:foo$)/m     true
\nfoo =~ /(?^:foo$)/s   true
\nfoo =~ /(?^:foo$)/m   true
foobar =~ /(?^:foo$)/s  false
foobar =~ /(?^:foo$)/m  false
bar\nfoo\n =~ /(?^:foo$)/s      true
bar\nfoo =~ /(?^:foo$)/m        true
bar\nfoo\n =~ /(?^:foo$)/       true
foo\nbar\n =~ /(?^:foo$)/       false
fred\nfoo\nbar\n =~ /(?^:foo$)/         false
fred\nfoo\nbar\n =~ /(?^:foo$)/         false
foo =~ /(?^:foo$)/      true
foobar =~ /(?^:foo$)/   false
\nfoo =~ /(?^:foo$)/    true
[download]

                /m      /s      none
foo/bar/        F       F       F
fred/foo/bar    F       F       F
foo             T       T       T
/foo            T       T       T
foobar          F       F       F
bar/foo/        T       T       T
bar/foo         T       T       T
[download]

In none of these situations did /m or /s produce a different result from each other. And in all cases, just having / with nothing after it produced the same results as the other two with options after them. I am not clear at all about the purpose of /m and /s (or the original purpose of $*, for that matter).

If anyone can clear this up, or can suggest situations I didn't test, I would be grateful.

sciguy