Line Filter

When to use?

Use it to extract only lines containing a specific error message from a server log, or to remove lines without a keyword to keep just the data you need — handy where grep is unavailable.

How to use

• Paste text.
• Enter keywords to include or exclude.
• Copy the result with only matching lines.

Input Explanation

Enter the source text and condition keywords. Separate multiple keywords with line breaks and choose include/exclude mode.

Calculation Basis

It splits the text by line breaks, checks each line for the keywords, collects matching lines, and rejoins. With case-insensitive on, only the comparison string is lowercased.

Usage Examples

• Filter logs - Quickly extract only lines with ERROR or WARN from a server log.
• Remove unneeded lines - Exclude unneeded lines like comments or blanks to clean up.
• Narrow down data - Keep only lines with a keyword from large text to narrow your analysis.

Examples

• Include "ERROR" → extract only lines containing ERROR from a log
• Exclude "DEBUG" → keep the log with DEBUG messages removed

Cautions

• Counts can vary by how spaces and line breaks are handled.
• A case-insensitive option is provided.

Guides

Isolating error lines from large logs

When a server log runs to tens of thousands of lines, filter by a target word such as "ERROR" or an IP range to condense the file down to only the lines that matter for debugging.

Flexible matching with regular expressions

Beyond plain text matching, enable regex mode to keep only lines that match a pattern such as a date format or a postal-code shape for more advanced preprocessing.

FAQ

Is it case-sensitive?

A case-insensitive option is provided.

Can I use multiple keywords?

Yes, apply multiple keywords with OR (matches any).

Can I use include and exclude together?

Keep desired lines with include, and filter out unneeded ones with exclude.

Can I copy the result?

Yes. Copy the collected filtered lines to use right away.

Related Tools

• Prefix/Suffix Adder - Add a prefix (front) and suffix (back) string to each line in bulk.
• Line Sorter - Sort each line of text in ascending/descending order, or shuffle randomly.
• Duplicate Line Remover - Remove duplicate lines from text, keeping only unique lines.
• Text Highlighter - Highlight multiple keywords in text and see found keywords and match counts in real time.
• Character Counter - Count characters with and without spaces, and line count, in real time.
• Byte Counter - Calculate the byte length of text when stored as UTF-8.