How to Search for Text Inside Files in Linux

Find which files contain a word, and exactly where.

Short answer

$ grep -rn "text" .

Searches every file under the current directory and prints each match with its filename and line number. This is the form worth committing to memory.

grep searches inside files; find searches for files. Confusing the two costs beginners a lot of time. For "where is this string used?", grep is the answer, and three flags cover almost every real use: -r to recurse, -n for line numbers, -i to ignore case.

Step by step

1 Search recursively with line numbers

$ grep -rn "DATABASE_URL" .

Every match under the current directory, each prefixed with file:line. That prefix is what lets you jump straight to the place that matters.

2 Ignore case

$ grep -rni "error" logs/

Matches Error, ERROR and error alike. Log files rarely agree on capitalisation.

3 List only the file names

$ grep -rl "old-domain.com" .

Useful when you care about which files are affected rather than the matches themselves, and it feeds neatly into a bulk replacement with xargs and sed.

4 Show surrounding context

$ grep -B2 -A5 "Exception" app.log

Two lines before and five after each match. Indispensable for reading stack traces, where the error line alone tells you almost nothing.

5 Skip the noise

$ grep -rn "TODO" . --exclude-dir={node_modules,.git} --include="*.js"

Excluding dependency directories turns a slow, cluttered search into an instant, readable one.

Tips worth knowing

Install ripgrep (`rg`) if you can: it respects .gitignore, skips binaries automatically and is dramatically faster on large repositories.
Searching for text with dots, brackets or dollars? Use grep -F to treat the pattern literally instead of as a regex.
Count instead of listing with -c, and invert the match with -v to hide what you have already seen.
Piping works too: any command output can be searched, `ps aux | grep nginx`, `journalctl -u app | grep -i timeout`.

Frequently asked questions

What is the difference between grep and find?

grep looks at the contents of files; find looks for files by name, size, date or type. "Which file mentions X" is grep; "where is the file called X" is find.

How do I search only certain file types?

grep -rn "text" . --include="*.py" restricts the search to Python files. Repeat --include for several patterns.

Why is my search so slow?

You are almost certainly scanning node_modules, .git or build directories. Exclude them with --exclude-dir, or use ripgrep, which does it by default.

How do I search compressed logs?

zgrep works exactly like grep but reads .gz files directly, with no need to decompress them first.

The commands behind it

grep

Find lines matching a pattern in files or piped input: the workhorse of text search.

find

Locate files anywhere in a directory tree by name, type, size, date, and act on them.

xargs

Turn a list of items into command arguments: the glue between pipelines and commands.

sed

Stream-edit text: substitute, delete lines, and edit files in place with -i.

Concepts involved: Regular expression · Pipe (|)

Choosing between tools

grep vs ripgrep (rg)

grep is everywhere; ripgrep is dramatically faster on code and respects .gitignore by default.

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