Most likely you want to use something like File::Basename to manipulate file names and paths.

Nice to see you are using warnings. You will find that strict (use strict;) helps a lot too.

opendir(DIR, "/tmp") || die "can't opendir $!";
while (my $file = readdir(DIR)) {
  next unless (-f "/tmp/$file");
  print $file."\n";
}
closedir DIR;
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my $fname = "/tmp/test.txt"; 
print $fname if(-e $fname);
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The -e function checks for existence of a given path (among other functions which check for other things, of course).

use strict;
my $dirpath = '/usr/C';
opendir(my $dir, $dirpath) or die "Error when using opendir $!";
my @namearr = grep {-f "$dirpath/$_"} readdir($dir); # get only files 
+and skip directories
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It is usually more efficient to use Perl's own internal functions rather than shelling out to an external command or program.

 @name1=$namearr[0]; is the same as saying  $name1[0]=$namearr[0]; so there is nothing in  $name1[2] to print out.

#!/usr/bin/perl -l

use warnings;
use strict;

use File::Spec::Functions qw(splitdir);

my $path = '/login/user/temp/file.txt';

my @names = splitdir $path;

print $names[0];  # prints: ""
print $names[1];  # prints: "login"
print $names[2];  # prints: "user"
print $names[3];  # prints: "temp"
print $names[4];  # prints: "file.txt"
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It's also good to ask all of your related questions in one post. I see you asked a similar question in How do i take the first 4 characters of any file name in a specified directory?