Grep (Global Regular Expression Print) filters lines of text, keeping only those that match a specified pattern. This tool implements grep with both plain text and regex matching.

What is head and tail?

Head returns the first N lines of a file; tail returns the last N lines. Both are classic Unix commands commonly used to preview log files and data streams.

Text Line Filter — Grep, Head, Tail, Range

Text filtering is a foundational operation in data processing, log analysis, and software development. This tool brings the power of classic Unix command-line tools — grep, head, tail — to the browser, with no installation required.

Filter Modes

Grep (contains): Keep only lines that contain the search text
Grep -v (not contains): Keep only lines that do NOT contain the search text
Regex filter: Keep lines matching a JavaScript regular expression
Head: Return the first N lines (like Unix head)
Tail: Return the last N lines (like Unix tail)
Line range: Extract a specific range of line numbers

Frequently Asked Questions

What regex syntax does this use?

This tool uses JavaScript regular expressions. Common patterns: ^start matches lines beginning with "start"; end$ matches lines ending with "end"; \d+ matches one or more digits; (foo|bar) matches "foo" or "bar".

Is this like the Unix grep command?

Yes, the Grep and Grep -v modes work like grep "pattern" file and grep -v "pattern" file respectively. The regex mode is like grep -E "regex" file.

Text Line Filter online

Grep, head, tail, and line range extraction — runs in your browser

Filter Modes

Frequently Asked Questions

What regex syntax does this use?

Is this like the Unix grep command?