Operation and MaintenanceLinux Operation and MaintenanceComprehensive explanation of the usage of grep command under Linux
To learn the Linux system, you must master the grep command. The grep command is used to find matching lines in files or standard output. Its power is that it supports regular expressions. In daily work, grep is definitely one of the most used commands.
Note: This article only introduces the usage of grep, and does not introduce regular expressions.
Let’s take a look at some of its common options and their meanings:
Options
- ##-i Ignore case when searching
- -n List all matching lines and display the line number
- -v Reverse selection
- -c Only output the number of matching lines
- -l Only list the file names that match, do not list specific matching lines
- -h Does not display file names when querying multiple files
- -r Recursive search
- -q Disables output of any results, exited status indicates search Is it successful?
- --color=auto Display the found keywords with color
- -E, --extended-regexp PATTERN Yes An extensible regular expression (abbreviated as ERE)
- -B, --before-context=NUM Print NUM lines starting with text
- -A, --after-context=NUM Print NUM lines ending with text
# 加上-i选项，忽略大小写 # grep -i timezone /usr/local/php/etc/php.ini ; Defines the default timezone used by the date functions ; http://php.net/date.timezone date.timezone = PRCgrep supports searching in multiple files
# 这里我们加上-n选项，输出文件的行号 # grep -in stdio itoa.c quicksort.c itoa.c:2:#include <stdio.h> quicksort.c:1:#include <stdio.h>The reverse selection -v is used. When I run a program and want to see if the program still exists in the process, I can use the following method
# ps aux | grep curl.php root 14374 98.3 1.2 277844 12396 pts/0 R+ 07:54 1:07 php curl.php root 14404 0.0 0.0 112664 984 pts/2 R+ 07:55 0:00 grep --color=auto curl.phpThere is a problem here, we You need to use -v to filter out the process of grep itself
# ps aux | grep curl.php | grep -v grep root 14374 98.5 1.2 277844 12396 pts/0 R+ 07:54 2:36 php curl.phpWe want to count the number of lines containing root in the last command, so we need to use the -c option here.
# last | grep -c root 353There is often a need to replace certain text in files in batches, so how do you know which files these texts are in. grep can do it, with the -l option
# find . -type f -exec grep -l define {} \;
./find.c
./itoa2.c
./wc.c
./test.c
./wordcnt.c
./longestline.c
./cal.c
./sortline2.c
./sortline.c
./found.c
./atof.c Let’s look at another example. This example uses the -E extended regular rule. We want to filter out the comment lines and blank lines in the php.ini file
grep -vE '^;|^$' /usr/local/php/etc/php.iniThere is also a commonly used option -r, which can be used to recursively search all files in the current directory and subdirectory files. Next, we want to check what footer files are in the website directory. We can use the following command to find
grep -rn footer ./
The above is the detailed content of Comprehensive explanation of the usage of grep command under Linux. For more information, please follow other related articles on the PHP Chinese website!
Linux: A Look at Its Fundamental StructureApr 16, 2025 am 12:01 AMThe basic structure of Linux includes the kernel, file system, and shell. 1) Kernel management hardware resources and use uname-r to view the version. 2) The EXT4 file system supports large files and logs and is created using mkfs.ext4. 3) Shell provides command line interaction such as Bash, and lists files using ls-l.
Linux Operations: System Administration and MaintenanceApr 15, 2025 am 12:10 AMThe key steps in Linux system management and maintenance include: 1) Master the basic knowledge, such as file system structure and user management; 2) Carry out system monitoring and resource management, use top, htop and other tools; 3) Use system logs to troubleshoot, use journalctl and other tools; 4) Write automated scripts and task scheduling, use cron tools; 5) implement security management and protection, configure firewalls through iptables; 6) Carry out performance optimization and best practices, adjust kernel parameters and develop good habits.
Understanding Linux's Maintenance Mode: The EssentialsApr 14, 2025 am 12:04 AMLinux maintenance mode is entered by adding init=/bin/bash or single parameters at startup. 1. Enter maintenance mode: Edit the GRUB menu and add startup parameters. 2. Remount the file system to read and write mode: mount-oremount,rw/. 3. Repair the file system: Use the fsck command, such as fsck/dev/sda1. 4. Back up the data and operate with caution to avoid data loss.
How Debian improves Hadoop data processing speedApr 13, 2025 am 11:54 AMThis article discusses how to improve Hadoop data processing efficiency on Debian systems. Optimization strategies cover hardware upgrades, operating system parameter adjustments, Hadoop configuration modifications, and the use of efficient algorithms and tools. 1. Hardware resource strengthening ensures that all nodes have consistent hardware configurations, especially paying attention to CPU, memory and network equipment performance. Choosing high-performance hardware components is essential to improve overall processing speed. 2. Operating system tunes file descriptors and network connections: Modify the /etc/security/limits.conf file to increase the upper limit of file descriptors and network connections allowed to be opened at the same time by the system. JVM parameter adjustment: Adjust in hadoop-env.sh file
How to learn Debian syslogApr 13, 2025 am 11:51 AMThis 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
How to choose Hadoop version in DebianApr 13, 2025 am 11:48 AMWhen choosing a Hadoop version suitable for Debian system, the following key factors need to be considered: 1. Stability and long-term support: For users who pursue stability and security, it is recommended to choose a Debian stable version, such as Debian11 (Bullseye). This version has been fully tested and has a support cycle of up to five years, which can ensure the stable operation of the system. 2. Package update speed: If you need to use the latest Hadoop features and features, you can consider Debian's unstable version (Sid). However, it should be noted that unstable versions may have compatibility issues and stability risks. 3. Community support and resources: Debian has huge community support, which can provide rich documentation and
TigerVNC share file method on DebianApr 13, 2025 am 11:45 AMThis article describes how to use TigerVNC to share files on Debian systems. You need to install the TigerVNC server first and then configure it. 1. Install the TigerVNC server and open the terminal. Update the software package list: sudoaptupdate to install TigerVNC server: sudoaptinstalltigervnc-standalone-servertigervnc-common 2. Configure TigerVNC server to set VNC server password: vncpasswd Start VNC server: vncserver:1-localhostno
Debian mail server firewall configuration tipsApr 13, 2025 am 11:42 AMConfiguring a Debian mail server's firewall is an important step in ensuring server security. The following are several commonly used firewall configuration methods, including the use of iptables and firewalld. Use iptables to configure firewall to install iptables (if not already installed): sudoapt-getupdatesudoapt-getinstalliptablesView current iptables rules: sudoiptables-L configuration
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
Dreamweaver Mac version
Visual web development tools
PhpStorm Mac version
The latest (2018.2.1) professional PHP integrated development tool
SublimeText3 English version
Recommended: Win version, supports code prompts!
DVWA
Damn Vulnerable Web App (DVWA) is a PHP/MySQL web application that is very vulnerable. Its main goals are to be an aid for security professionals to test their skills and tools in a legal environment, to help web developers better understand the process of securing web applications, and to help teachers/students teach/learn in a classroom environment Web application security. The goal of DVWA is to practice some of the most common web vulnerabilities through a simple and straightforward interface, with varying degrees of difficulty. Please note that this software
mPDF
mPDF is a PHP library that can generate PDF files from UTF-8 encoded HTML. The original author, Ian Back, wrote mPDF to output PDF files "on the fly" from his website and handle different languages. It is slower than original scripts like HTML2FPDF and produces larger files when using Unicode fonts, but supports CSS styles etc. and has a lot of enhancements. Supports almost all languages, including RTL (Arabic and Hebrew) and CJK (Chinese, Japanese and Korean). Supports nested block-level elements (such as P, DIV),
