Does Duplicate Nth Line upload my file or text to Tool-You servers?

No. Duplicate Nth Line runs in this browser tab. Files stay on the device. Limit note: 1-based line index. Empty fails.

Should I use Drop First Line instead of Duplicate Nth Line?

Use Duplicate Nth Line when you need Duplicate a 1-based line index. Use Drop First Line when you need Remove the first line. They share a category (Developer) but not the same job.

Duplicate Nth Line

Duplicate a 1-based line index.

Duplicates the n-th line in place. Unlike Drop First Line this inserts a copy. Line index out of range fails. Empty fails.

What Duplicate Nth Line does

Duplicates the n-th line in place. Unlike Drop First Line this inserts a copy. Line index out of range fails. Empty fails.

The interactive controls for Duplicate Nth Line load after this article so crawlers still read the instructions. Path /developer/duplicate-nth-line is the canonical address. Work happens on this device; Tool-You does not take a copy of the file or pasted text for Duplicate Nth Line.

How to use Duplicate Nth Line

Keep this tab on Duplicate Nth Line (/developer/duplicate-nth-line). Pasting into the wrong Developer tool (for example Drop First Line) changes the job.
Paste or type the input Duplicate Nth Line expects. Path hint: developer · duplicate nth line. Duplicate a 1-based line index.
Apply the Duplicate Nth Line action only. Drop Last Line is a different transform (Remove the last line.). Duplicates the n-th line in place. Unlike Drop First Line this inserts a copy. Line index out of range fails. Empty fails.
Copy the output of Duplicate Nth Line if you need it elsewhere. Size/complexity still follows: 1-based line index. Empty fails.
If the text job is actually Remove the first line., leave Duplicate Nth Line and open Drop First Line.

When not to use Duplicate Nth Line

Skip Duplicate Nth Line when a neighbor tool matches better — start with Drop First Line or Drop Last Line — or when the description already warns the job will fail. In the tool’s own words: Duplicates the n-th line in place. Unlike Drop First Line this inserts a copy. Line index out of range fails. Empty fails.

Questions about Duplicate Nth Line

What does Duplicate Nth Line do that other Developer pages on this site do not?: Duplicates the n-th line in place. Unlike Drop First Line this inserts a copy. Line index out of range fails. Empty fails. Short version: Duplicate a 1-based line index.
Does Duplicate Nth Line upload my file or text to Tool-You servers?: No. Duplicate Nth Line runs in this browser tab. Files stay on the device. Limit note: 1-based line index. Empty fails.
Should I use Drop First Line instead of Duplicate Nth Line?: Use Duplicate Nth Line when you need Duplicate a 1-based line index. Use Drop First Line when you need Remove the first line. They share a category (Developer) but not the same job.
What are the limits of Duplicate Nth Line?: 1-based line index. Empty fails. Also: Duplicates the n-th line in place. Unlike Drop First Line this inserts a copy. Line index out of range fails. Empty fails.