


How to read the last few lines in cat in linux
In Linux, you can use the cat command with the tail command to view the last few lines of the file; the cat command is used to connect files and print to the standard output device, and the tail command can be used to view the contents of the file. When tail When the parameter of the command is set to "-n", the contents of the specified lines at the end of the file can be displayed. The syntax is "cat specified file | tail -n displays the number of the last few lines".
#The operating environment of this tutorial: linux7.3 system, Dell G3 computer.
How to read the last few lines of cat in Linux
The cat (full English spelling: concatenate) command is used to connect files and print to the standard output device.
Syntax format
cat [-AbeEnstTuv] [--help] [--version] fileName
Parameter description:
-n or --number: Number all output lines starting from 1 .
-b or --number-nonblank: Similar to -n, except that blank lines are not numbered.
-s or --squeeze-blank: When encountering more than two consecutive blank lines, replace them with one blank line.
-v or --show-nonprinting: Use the ^ and M- symbols except LFD and TAB.
-E or --show-ends : Show $ at the end of each line.
-T or --show-tabs: Display TAB characters as ^I.
-A, --show-all: Equivalent to -vET.
-e: Equivalent to the "-vE" option;
-t: Equivalent to the "-vT" option;
tail command can be used to view the contents of the file,
Command format:
tail [参数] [文件]
Parameters:
-f Loop reading
-q Do not display processing information
-v Display detailed processing information
-c
The number of bytes displayed ##-n
Display the last n lines of the file
The example is as follows
Combine the three commands to view line x to line Y of the file. Syntax format 1: Starting from line X, display line Y. That is, display the Y rowcat filename | tail -n +X | head -n Y
cat requirements.txt | tail -n +3000 | head -n 1000
- tail -n 1000: Start displaying from line 1000, and display the following
- head -n 1000: Display the first 1000 lines
- Recommended learning:
Linux video tutorial
The above is the detailed content of How to read the last few lines in cat in linux. For more information, please follow other related articles on the PHP Chinese website!

Hot AI Tools

Undresser.AI Undress
AI-powered app for creating realistic nude photos

AI Clothes Remover
Online AI tool for removing clothes from photos.

Undress AI Tool
Undress images for free

Clothoff.io
AI clothes remover

AI Hentai Generator
Generate AI Hentai for free.

Hot Article

Hot Tools

Notepad++7.3.1
Easy-to-use and free code editor

SublimeText3 Chinese version
Chinese version, very easy to use

Zend Studio 13.0.1
Powerful PHP integrated development environment

Dreamweaver CS6
Visual web development tools

SublimeText3 Mac version
God-level code editing software (SublimeText3)

Hot Topics



The steps to start Apache are as follows: Install Apache (command: sudo apt-get install apache2 or download it from the official website) Start Apache (Linux: sudo systemctl start apache2; Windows: Right-click the "Apache2.4" service and select "Start") Check whether it has been started (Linux: sudo systemctl status apache2; Windows: Check the status of the "Apache2.4" service in the service manager) Enable boot automatically (optional, Linux: sudo systemctl

When the Apache 80 port is occupied, the solution is as follows: find out the process that occupies the port and close it. Check the firewall settings to make sure Apache is not blocked. If the above method does not work, please reconfigure Apache to use a different port. Restart the Apache service.

This article describes how to effectively monitor the SSL performance of Nginx servers on Debian systems. We will use NginxExporter to export Nginx status data to Prometheus and then visually display it through Grafana. Step 1: Configuring Nginx First, we need to enable the stub_status module in the Nginx configuration file to obtain the status information of Nginx. Add the following snippet in your Nginx configuration file (usually located in /etc/nginx/nginx.conf or its include file): location/nginx_status{stub_status

The steps to start an Oracle listener are as follows: Check the listener status (using the lsnrctl status command) For Windows, start the "TNS Listener" service in Oracle Services Manager For Linux and Unix, use the lsnrctl start command to start the listener run the lsnrctl status command to verify that the listener is started

This article introduces two methods of configuring a recycling bin in a Debian system: a graphical interface and a command line. Method 1: Use the Nautilus graphical interface to open the file manager: Find and start the Nautilus file manager (usually called "File") in the desktop or application menu. Find the Recycle Bin: Look for the Recycle Bin folder in the left navigation bar. If it is not found, try clicking "Other Location" or "Computer" to search. Configure Recycle Bin properties: Right-click "Recycle Bin" and select "Properties". In the Properties window, you can adjust the following settings: Maximum Size: Limit the disk space available in the Recycle Bin. Retention time: Set the preservation before the file is automatically deleted in the recycling bin

To restart the Apache server, follow these steps: Linux/macOS: Run sudo systemctl restart apache2. Windows: Run net stop Apache2.4 and then net start Apache2.4. Run netstat -a | findstr 80 to check the server status.

In Debian systems, readdir system calls are used to read directory contents. If its performance is not good, try the following optimization strategy: Simplify the number of directory files: Split large directories into multiple small directories as much as possible, reducing the number of items processed per readdir call. Enable directory content caching: build a cache mechanism, update the cache regularly or when directory content changes, and reduce frequent calls to readdir. Memory caches (such as Memcached or Redis) or local caches (such as files or databases) can be considered. Adopt efficient data structure: If you implement directory traversal by yourself, select more efficient data structures (such as hash tables instead of linear search) to store and access directory information

This guide will guide you to learn how to use Syslog in Debian systems. Syslog is a key service in Linux systems for logging system and application log messages. It helps administrators monitor and analyze system activity to quickly identify and resolve problems. 1. Basic knowledge of Syslog The core functions of Syslog include: centrally collecting and managing log messages; supporting multiple log output formats and target locations (such as files or networks); providing real-time log viewing and filtering functions. 2. Install and configure Syslog (using Rsyslog) The Debian system uses Rsyslog by default. You can install it with the following command: sudoaptupdatesud
