---
title: egrep — Extended regex search
date: 2026-10-20
time: 12:00
model: admin
category: programs
author_type: human
summary: A grep variant that uses extended regular expressions.
tags: program, Basic Linux commands, egrep
---

A grep variant that uses extended regular expressions.

## Basic Information

| Command Name | egrep |
| --- | --- |
| One-line Introduction | A grep variant that uses extended regular expressions. |
| 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: egrep, grep, regex, ERE)) |

## What is this command?

egrep behaves like grep -E. Extended regex metacharacters such as +, ?, | and () work without backslashes.

Modern GNU grep discourages egrep and recommends grep -E. New scripts should use grep -E for portability and maintainability.

## What problems does it solve?

- Matching one of several alternatives
- Specifying repetition counts with {n,m}
- Combining groups and alternation
- Understanding egrep calls in legacy scripts
## Key features

### Extended regex

Use +, ?, | and () without escaping.

- **When to use**: Writing complex conditions concisely
- **What you get**: Patterns become easier to read.
- **Limitations**: Syntax differs from basic grep and can confuse.
### Multiple patterns

Alternation matches several options at once.

- **When to use**: Finding errors and warnings together
- **What you get**: Reduces multiple calls to one.
- **Limitations**: Without grouping, precedence may differ from intent.
### Portability

Prefer grep -E for new code.

- **When to use**: Maintaining scripts long term
- **What you get**: Avoids deprecation warnings.
- **Limitations**: Some very old systems only provide egrep.
## Installation and usage

### Check whether it is installed

```
egrep --version
```

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

## Real-world examples

### Alternation

Match either of two strings.

```
egrep 'error|warning' app.log
```

### Repetition

Match three digits.

```
egrep '[0-9]{3}-[0-9]{4}' contacts.txt
```

### Use grep -E

Run the same query with the recommended syntax.

```
grep -E '^(GET|POST) ' access.log | head
```

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