CODEWITHSUNDEEP
perlfilenewlineblank-line
wuyefeibao
wuyefeibao

Reputation: 237

Delete the first line using Tie::File without leave a newline at the end of the file

I use the following code to delete the first line of a file:

use Tie::File;
tie @task_queue, 'Tie::File', $queue_path or die $!;
shift @task_queue;
$#task_queue -= 1;
untie @task_queue;

The file content is like:

line1
line2
line3

But when I use the code, it will delete the line1 but leave a newline at the end of the file like this:

line2
line3
# <- here is a blank line

Since I use this file as a queue, if I add some new line after, it will become:

line2
line3
# <- here is a blank line
line4

So is there any way to avoid leaving a blank line when using Tie::File to delete the first line?

Upvotes: 0

Views: 180

Answers (2)

wuyefeibao
wuyefeibao

Reputation: 237

Thanks to all that help with this. I found a solution, it's not beautiful code but works. I also found that the blank line is still generated even if I do only tie and untie(no action between them). It may be some design issue of the module.

use Tie::File;
tie @task_queue, 'Tie::File', $queue_task_path or die $!;
shift @task_queue;
untie @task_queue;
print("Removing the blank line.\n");
my $queue_task_file_size = -s $task_queue;
truncate($task_queue, $queue_task_file_size - 1);

Upvotes: 0

Chris Charley
Chris Charley

Reputation: 6613

I don't know if this is a good solution, but it removes blank lines at the end of the file.

while ($task_queue[-1] eq '') {
    pop @task_queue;
}

Upvotes: 1

Related Questions