bash
grep ERROR app.logNotes
The simplest grep usage searches for matching lines.
Linux grep and ripgrep Cheat Sheet
Search text with grep, egrep, fgrep, and ripgrep including regex, file globs, recursion, and context.
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Basic grep
Match lines and patterns in files and streams.
bash
grep -i timeout app.logNotes
Useful when log or text casing is inconsistent.
bash
grep -n TODO src/app.jsNotes
Line numbers make it easier to jump directly to a match.
bash
grep -c ERROR app.logNotes
Good for quick metrics and health checks in scripts.
bash
grep -v '^#' .envNotes
Commonly used to skip comment lines or blank lines after combining with another expression.
bash
grep -w user auth.logNotes
`-w` prevents matching terms that only appear inside larger strings.
Regex with grep
Use regular expressions for more powerful matches.
Use extended regex
Enable `+`, `?`, and alternation without heavy escaping.
bashANYgrepregexextended
bash
grep -E 'warn|error|fatal' app.logNotes
Equivalent to traditional `egrep`.
bash
grep -F 'a+b*c' notes.txtNotes
Equivalent to traditional `fgrep` and useful when searching for symbols literally.
bash
grep '^ERROR.*timeout$' app.logNotes
Anchors let you constrain a match to the full line shape.
bash
grep -n '^$' file.txtNotes
Helpful for validating formatting or splitting sections.
bash
grep -n '[^[:space:]]' file.txtNotes
Useful when skipping whitespace-only lines.
Recursive Search
Search across directories and source trees.
bash
grep -R 'TODO' src/Notes
Recursive search is a common way to scan a codebase.
Recursive search with line numbers
Show file names and line numbers for matches.
bashANYgreprecursiveline-number
bash
grep -Rn 'TODO' src/Notes
One of the most useful codebase-search commands.
Only search matching file names
Restrict recursive search to certain extensions.
bashANYgrepincluderecursive
bash
grep -R --include='*.ts' 'useEffect' src/Notes
Helpful for codebases containing mixed file types.
bash
grep -R --exclude-dir=node_modules 'axios' .Notes
Excluding generated or vendored folders makes searches much faster.
bash
grep -Rl 'TODO' src/Notes
Useful when you only care which files match, not the lines themselves.
Context Around Matches
Show surrounding lines to understand matches better.
bash
grep -B 3 ERROR app.logNotes
Before-context is useful when logs explain the lead-up to an error.
bash
grep -A 5 ERROR app.logNotes
After-context often shows stack traces or follow-up log lines.
bash
grep -C 2 ERROR app.logNotes
`-C` gives balanced context and is often the most convenient option.
ripgrep (rg)
Fast recursive search for code and text.
bash
rg TODO src/Notes
ripgrep respects common ignore files and is usually faster than recursive grep for code.
bash
rg -n 'useState' src/Notes
Line numbers are included by default in many rg outputs, but `-n` makes it explicit.
bash
rg -g '*.ts' 'useEffect' src/Notes
Globs help narrow large code searches to relevant files.
bash
rg -F 'http://localhost:3000' .Notes
Useful for URLs or strings containing regex metacharacters.
bash
rg -l 'TODO|FIXME' src/Notes
Great when triaging or collecting files to edit.
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