How to use it
- Paste the text, one item per line.
- Type the word, phrase or pattern.
- Choose Keep (only matching lines stay) or Remove (matching lines are deleted).
- Switch to Regex if you need a pattern, and turn off Ignore case to match case exactly.
How it works
The text is split into lines. Each line is tested for the pattern, and the lines whose result fits your choice are joined back with line breaks. A line break at the very end of the text is not counted as an extra empty line.
Worked example
In the sample, keeping lines that contain “error” with case ignored leaves two lines: the ERROR line and the “error: cannot write file” line. With the case option off, only the second one stays. Removing them leaves the three other lines.
Tips
In regex mode, ^2026-11-01 10:0 matches lines starting with that text, and ERROR|WARN matches either word. A pattern with nested repeats on very long lines can be slow, as in any regex engine.