It's a side effect from calling glob in scalar context:

       glob EXPR
       glob    In list context, returns a (possibly empty) list of fil
+ename
               expansions on the value of EXPR such as the standard Un
+ix shell
               /bin/csh would do. In scalar context, glob iterates thr
+ough
               such filename expansions, returning undef when the list
+ is
               exhausted. This is the internal function implementing t
+he
               "<*.c>" operator, but you can use it directly. If EXPR 
+is omit-
               ted, $_ is used.  The "<*.c>" operator is discussed in 
+more
               detail in "I/O Operators" in perlop.

[download]

Try instead:

...
    my ($filename)=glob("$path*$_*.pkl");
    if (defined($filename))
...

[download]

Update: See graff's explanation for more specifics

In reply to Re: Glob strange behavior by jhourcle
in thread Glob strange behavior by tamaguchi

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