---
title: tail — Linux basic command
date: 2026-10-19
time: 12:00
model: admin
category: programs
author_type: human
summary: Outputs the end part (last few lines) of a file or tracks its changes in real time.
tags: program, Basic Linux commands, tail
---

A command that outputs only the end part (the last few lines) of a file or tracks it in real time.

## Basic Information

| Command Name | tail |
| --- | --- |
| One-line Description | A command that outputs only the end part (the last few lines) of a file or tracks it in real time. |
| Provided by | GNU coreutils (pre-installed on all Linux distributions) |
| Official Documentation | https://man7.org/linux/man-pages/man1/tail.1.html |
| Supported Operating Systems | Linux, macOS, BSD, WSL |
| Installation Required | Pre-installed (no separate installation needed) |
| Category | Linux basic command (tags: file output, real-time tracking, log, Linux, basic) |

## What is this command?

tail is a command that outputs only a specified number of lines (default 10 lines) from the end of a file. Using the -f option, it outputs in real time whenever new content is added to the file, making it essential for log monitoring.

While head shows the beginning of a file, tail shows the end. Using both tools together allows you to quickly understand a file's structure.

## What problem does it solve?

- Checks the end of a long log file.
- Monitors logs being recorded in real time.
- Checks recent logs when an error occurs.
- Checks the results at the end of a file.
## Key Features

### Default 10-line output

Outputs the last 10 lines of a file.

- **Use Case**: When you need to quickly check recent records.
- **Result**: You can view the content at the end of the file.
- **Limitation**: If the file has fewer than 10 lines, the entire content is output.
### Real-time tracking (-f)

Outputs in real time when new content is added to the file.

- **Use Case**: When monitoring log files in real time.
- **Result**: New logs are automatically displayed as they are recorded.
- **Limitation**: Tracking may stop if the file is deleted and recreated.
### Line count specification (-n)

Specifies the number of lines to output using the -n option.

- **Use Case**: When you need to check a specific number of lines.
- **Result**: Outputs the specified number of lines.
- **Limitation**: Specifying 0 or a negative number will cause an error.
### Simultaneous tracking of multiple files

Tracks the ends of multiple files simultaneously.

- **Use Case**: When monitoring multiple service logs on one screen.
- **Result**: New content from all files is displayed in order.
- **Limitation**: With many files, the screen can become cluttered.
## Installation and Execution

### Verify pre-installation

It is included by default in all Linux distributions.

```
which tail
tail --version
```

### Installation (lightweight environments)

It is usually already installed.

```
sudo apt install coreutils   # Debian/Ubuntu
```

## Practical Usage Examples

### Basic output

Checks the last 10 lines of a file.

```
# Output last 10 lines
tail /var/log/syslog

# Multiple files
tail file1.txt file2.txt

# With a pipe
ps aux | tail -5
```

### Line count specification

Outputs the desired number of lines.

```
# Only the last 5 lines
tail -n 5 /var/log/syslog

# Only the last 20 lines
tail -20 /var/log/syslog

# Last 100 recent logs
tail -100 /var/log/nginx/error.log
```

### Real-time log monitoring

Views content being added to a file in real time.

```
# Real-time tracking
tail -f /var/log/syslog

# Track multiple logs simultaneously
tail -f /var/log/nginx/access.log /var/log/nginx/error.log

# Track from a specific line count
tail -n 20 -f /var/log/syslog
```

---
Source (HTML): https://games.aidebatehub.com/programs/linux/basics/tail.html
This file is an auto-generated Markdown twin of the DevHub document.