problem with `glob` function in perl

I want to get a list of all the files whose name looks like : $res_dir/$line/$fub_name*.istf

meaning: in directory $dir in sub directory $line a file that starts with $name and ends with .istf.

eac开发者_JAVA技巧h sub directory contains only 1 such file, but there are many sub directories. I've written this:

foreach $line (@arr){
    chomp ($line);
    $new_istf = glob ("$res_dir/$line/$fub_name*.istf");
    do something...

but it doesn't give me all the files, but only half of them. when I added the fallowing debug code:

if ($new_istf){
    print "\tdbug:: $res_dir/$line/$fub_name*.istf:\t'$new_istf'\n";
} else {
    print "\tdbug:: $res_dir/$line/$fub_name*.istf:\t''\n";
}

and the resulting output was:

    dbug:: RESULTS//791202_0_SA0/ieuni5cts*.istf:   'RESULTS//791202_0_SA0/ieuni5cts.mlc.xxx.x.istf'
    dbug:: RESULTS//791212_0_SA0/ieuni5cts*.istf:   ''
    dbug:: RESULTS//791241_0_SA0/ieuni5cts*.istf:   'RESULTS//791241_0_SA0/ieuni5cts.mlc.xxx.x.istf'
    dbug:: RESULTS//791248_0_SA0/ieuni5cts*.istf:   ''
    dbug:: RESULTS//791251_0_SA0/ieuni5cts*.istf:   'RESULTS//791251_0_SA0/ieuni5cts.mlc.xxx.x.istf'
    dbug:: RESULTS//791258_0_SA0/ieuni5cts*.istf:   ''
    dbug:: RESULTS//791272_0_SA0/ieuni5cts*.istf:   'RESULTS//791272_0_SA0/ieuni5cts.mlc.xxx.x.istf'
    dbug:: RESULTS//791273_0_SA1/ieuni5cts*.istf:   ''
    dbug:: RESULTS//791301_0_SA0/ieuni5cts*.istf:   'RESULTS//791301_0_SA0/ieuni5cts.mlc.xxx.x.istf'
    dbug:: RESULTS//791333_0_SA0/ieuni5cts*.istf:   ''
    dbug:: RESULTS//791349_0_SA0/ieuni5cts*.istf:   'RESULTS//791349_0_SA0/ieuni5cts.mlc.xxx.x.istf'
    dbug:: RESULTS//791357_0_SA0/ieuni5cts*.istf:   ''
    dbug:: RESULTS//791405_0_SA1/ieuni5cts*.istf:   'RESULTS//791405_0_SA1/ieuni5cts.mlc.xxx.x.istf'
    dbug:: RESULTS//791432_0_SA0/ieuni5cts*.istf:   ''
    dbug:: RESULTS//791434_0_SA0/ieuni5cts*.istf:   'RESULTS//791434_0_SA0/ieuni5cts.mlc.xxx.x.istf'
    dbug:: RESULTS//791459_0_SA0/ieuni5cts*.istf:   ''
    dbug:: RESULTS//791462_0_SA0/ieuni5cts*.istf:   'RESULTS//791462_0_SA0/ieuni5cts.mlc.xxx.x.istf'
    dbug:: RESULTS//791463_0_SA0/ieuni5cts*.istf:   ''
    dbug:: RESULTS//791467_0_SA0/ieuni5cts*.istf:   'RESULTS//791467_0_SA0/ieuni5cts.mlc.xxx.x.istf'
    dbug:: RESULTS//791471_0_SA1/ieuni5cts*.istf:   ''

but all those files exist. since glob suppose to work like the sell interpreter, i've checked it and when I do echo RESULTS//791463_0_SA0/ieuni5cts*.istf (and every other file that was not detected by glob, it gives the right file name.

I've also tried to run glob as a one liner with the paths that didn't give result, and it worked:

perl -e 'print glob("RESULTS//791467_0_SA0/ieuni5cts*.istf"),"\n"'

and it gave the right result as well

Where is the problem in my code?

---

From perldoc -f glob:

---

In list context, returns a (possibly empty) list of filename expansions on the value of EXPR such as the standard Unix shell /bin/csh would do. In scalar context, glob iterates through such filename expansions, returning undef when the list is exhausted.

---

The code posted is in scalar context.

See if calling it in list context solves the issue:

my ( $new_istf ) = glob ( "$res_dir/$line/$fub_name*.istf" );