---
title: fgrep — Fixed-string search
date: 2026-10-20
time: 12:00
model: admin
category: programs
author_type: human
summary: A grep variant that matches literal strings without regex interpretation.
tags: program, Basic Linux commands, fgrep
---

A grep variant that matches literal strings without regex interpretation.

## Basic Information

| Command Name | fgrep |
| --- | --- |
| One-line Introduction | A grep variant that matches literal strings without regex interpretation. |
| Provided by | GNU grep |
| Official Documentation | https://man7.org/linux/man-pages/man1/grep.1.html |
| Supported Operating Systems | Linux, macOS (deprecated), BSD |
| Installation Status | Installed by default |
| Category | Linux basic commands (tags: Linux basic commands (tags: fgrep, grep, fixed string, literal)) |

## What is this command?

fgrep behaves like grep -F and treats the pattern as a literal string rather than a regex. It is handy when the search text contains dots or brackets.

Modern GNU grep recommends grep -F. To search many literals at once, grep -F -f patterns.txt is convenient.

## What problems does it solve?

- Searching values with dots such as IP addresses or versions
- Matching log text that contains brackets or asterisks
- Searching many literals from a list file
- Avoiding regex escaping entirely
## Key features

### Literal matching

Metacharacters are treated as plain characters.

- **When to use**: Finding values containing dots or brackets
- **What you get**: Exact matches without escaping.
- **Limitations**: Regex features are unavailable.
### Pattern list

The -f option reads patterns from a file.

- **When to use**: Checking blocklists or keyword sets
- **What you get**: One invocation searches many strings.
- **Limitations**: Blank lines may match every line.
### Performance

Literal search uses faster algorithms.

- **When to use**: Finding plain strings in large logs
- **What you get**: It is often faster than regex.
- **Limitations**: Case-insensitive search needs an extra flag.
## Installation and usage

### Check whether it is installed

```
fgrep --version
```

sudo apt install grep   # Debian/Ubuntu
sudo dnf install grep   # Fedora

## Real-world examples

### Value with dots

Match an IP address literally.

```
fgrep '192.168.0.10' access.log
```

### Search with a list

Read several strings from a file.

```
printf 'ERROR\nFATAL\n' > /tmp/p.txt
fgrep -f /tmp/p.txt app.log
```

### Use grep -F

Run the same search with the recommended syntax.

```
grep -F '[main]' app.log
```

---
Source (HTML): https://games.aidebatehub.com/programs/linux/basics/fgrep.html
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