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A clearly defined rule produces an output that is easier to inspect.
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Prefix Lines
Add the same prefix to every following line while preserving line order and line breaks.
Predictable processing Source remains editable Separate result Copy-ready output
Private browser processing. Your input is processed on this device and is not sent to the Trexmi server.
INPUT Lines to prefix
Paste one or more lines while keeping the order and line breaks you want processed. Example: report
summary
Reading file…
Prefix Lines result
Review the transformed text, then copy or download it when needed.
About the tool
What Prefix Lines does
Prefix Lines is a focused browser utility that helps you add the same prefix to every following line while preserving line order and line breaks.
The workspace keeps the source available, applies one transparent operation, and displays the result separately. This makes the output easier to compare before it is published, imported, shared, or reused.
For important content, work from a complete source, keep an untouched backup, and verify context-sensitive values in the destination system.
How to use
- Paste. Add the complete source text.
- Configure. Enter any setting required by the tool.
- Run. Apply the named operation.
- Review. Compare source and result carefully.
- Copy. Use the output only after verification.
Built for the task
Why use Prefix Lines?
Focused controls, predictable output, and a workflow designed around this exact transformation.
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Source remains editable
The original content stays available for comparison and recovery.
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Separate result
Generated content is displayed independently from the source.
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Copy-ready workflow
Review the complete output before copying it into another system.
Useful answers
Questions about Prefix Lines
Practical details about input, output, privacy, limits, and the best way to use this tool.
01 Where is the prefix entered?
Enter the prefix on the first line and place the lines to transform underneath it.
02 Is the first line included in the output?
No. The first line is treated as the setting rather than source content.
03 Are blank lines prefixed?
Depending on the processor, blank rows may receive the prefix. Review the preview before copying.
04 Does it add a space automatically?
No. Include any required space inside the prefix itself.
05 Is line order preserved?
Yes. The following source lines remain in their original order.
06 Can I add numbering?
Only a fixed repeated prefix is added. Sequential numbering requires a different tool.
07 Can I remove the prefix later?
Yes, with find-and-replace or another cleanup step, provided the prefix is unambiguous.
08 How should I verify the result?
Check the first and last rows, blank lines, and whether the prefix includes the intended spacing or punctuation.
Prefix Lines — How Prefix Lines applies a repeated beginning
Prefix Lines treats the first input row as a fixed setting and adds it before every following source row. The original order and line boundaries remain visible in the generated result.
Review the source and generated result together, keep an untouched backup, and confirm the output in the destination system before relying on it.
Prefix Lines — Preparing the prefix correctly
The prefix is inserted exactly as entered. Add spaces, punctuation, symbols, or path separators directly to the setting so the output has the intended appearance.
Review the source and generated result together, keep an untouched backup, and confirm the output in the destination system before relying on it.
Prefix Lines — Lists, labels, paths, and code preparation
Common uses include bullets, labels, comment markers, URL paths, directory prefixes, CSS selectors, and repeated text fragments. Review syntax carefully when preparing code or import data.
Review the source and generated result together, keep an untouched backup, and confirm the output in the destination system before relying on it.
Prefix Lines — Blank lines and whitespace
Blank source rows may still be transformed, and existing leading spaces remain after the added prefix. Inspect whitespace-sensitive content before using the output.
Review the source and generated result together, keep an untouched backup, and confirm the output in the destination system before relying on it.
Prefix Lines — Preserving line order
The operation does not sort, deduplicate, or otherwise rearrange rows. Each line receives the same prefix in the same sequence as the source.
Review the source and generated result together, keep an untouched backup, and confirm the output in the destination system before relying on it.
Prefix Lines — Reversing and validating the change
Compare the source and result, confirm the first line was used only as the setting, and test a small sample in the destination. Keep a backup so the operation can be reversed safely.
Review the source and generated result together, keep an untouched backup, and confirm the output in the destination system before relying on it.
Related Trexmi tools
Continue with a related utility, another focused tool, or a complementary workflow. Keeping operations separate makes changes easier to understand and reverse.
External reference
For general string-processing concepts, consult the MDN String reference.