unix egrep

lowercase or uppercase letters[^ character table]//Match any characters that are not in the character listCutCut-c1-a//Extract the results of each line from the first character to the last character in a fileCut-c1-5 A//extract the result of each line from the first character to the 5th character in a fileCut-d:-f1/etc/shadow//Shadow each line in the file as: The result of the first segment of the split is extracted, that is, the user nameCut-d:-f1,6/etc/passwd//Each line in the passwd file is

About the Unix pipeline, this article is very thorough: http://blog.petersobot.com/pipes-and-filters Pipeline (pipelines) is a very useful architecture model in modern software engineering, which was first used in Unix system, and there is a saying. If UNIX is the greatest invention of computer civilization, the pipe pipeline under

15. The UNIX domain protocol is a way to perform client/server communications on a single host, using APIs that perform client/server communications on different hosts UNIX domain sockets are typically one-fold faster than TCP sockets on the same host at both ends of the communication UNIX domain sockets can be used to pass descriptors between different processes

Today's topic is how to find a UNIX chicken, I think it is necessary for a person who has a lot of Windows chicken without a UNIX chicken. Don't wordy, straight into the business. Why do you think I'm looking for a chicken with X-laser? Because all of our operations are carried out on 3389 of chickens. First we all go to the same terminal, (premise: The terminal is open to each other, rather than you do, so

In a Linux system, there is a very important directory--/usr directory. On the origin of this directory name, the main online has the following several statements: User's initials User shareable read-only abbreviation Abbreviation for Unix/user System Resources Abbreviation for Unix/user Software Resources Most versions of the Linux/usr directory are currently placed primarily with executables and firs

The address data structure of the socket has different forms depending on the system and the network environment. In order for the different format addresses to be passed into the socket function, the address structure must be forced to be converted to: struct sockaddr{ sa_family_t sa_family;/* address family*/ char sa_data[];/* Variable-length address*/ ... }; The socket implementation is free to add additional members and to define the size of the Sa_data member. For example,

How to Learn C language in UNIX/Linux, unixlinux I. Tools "To do good deeds, you must first sharpen your tools ". Programming is a very practical job. In your future studies or work, you will often deal with the following tools. The following lists the software and tools that are often used to learn C programming. 1. Operating System It is easy to learn C in UNIX or Linux systems. Therefore, before you star

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Although the C language has been in existence for nearly 30 years, its charm has not diminished. The C language continues to attract a large number of developers who have to learn new skills in order to write, transplant, or maintain applications. This article is written to meet the needs of beginners in C language or developers who want to improve their C language. Hope to help you with your study and work. You may not agree with some of these methods, but we hope you'll like some of them. Th

Article Title: analyze the advantages and disadvantages of Unix operating systems. Linux is a technology channel of the IT lab in China. Includes basic categories such as desktop applications, Linux system management, kernel research, embedded systems, and open source. Nowadays, Windows is no longer satisfactory. People need a more scalable, reliable, and high-performance environment. You may be running Oracle financial software, eaglesoft, and many E

UNix programming Art17-Point Programming philosophical principles in --- High standards for design developers Translator: July November January 13, 2011. References: The art of Unix programmingBy Eric Steven Raymond Author's Note: This article is based on the English version of the Unix programming art book, the first chapter, the translation.During

Two security questions about UNIX Networks In recent years, many articles have successively introduced a so-called Secure UNIX shutdown user. The main idea is to add the/etc/shutdown command or the/etc/haltsys command at the end of the/etc/passwd file or the/etc/shadow file to replace/bin. /SH command. In this way, even if someone knows the password of the shutdown user (or does not set the password of the

In fact, every hacker has his own unique method. I have collected a lot of information about intrusions into the website server, but because of the actual situation, many methods are often ineffective. It can be seen that the situation of each website is different, and intruders need to treat it differently. Assume that the line in Shenzhen is much better than that in Beijing, which makes it easy for the dictionary to use, so that users in Shenzhen can use this advantage to attack passwords onli

15 practical Linux/Unix tape management commands for the system administrator Tape equipment should only be used for regular file archiving or data is transferred from one server to another. Generally, tape devices are connected to Unix machines and controlled by mt or MTCs. We strongly recommend that you back up all data to disks (maybe in the cloud) and tape devices at the same time. In this tutorial, you

Summary Oracle Database is a well-known leading database system on Unix hardware platforms. Oracle users and administrators are therefore familiar with the Oracle architecture on the UNIX platform and the tools and skills above it, and get the greatest benefit from their databases. On the contrary, Oracle architecture on windows is not so widely known. This article starts from a "> DBAThe key similarities a

service department. If Microsoft's api is vague, do you have to worry about it? Haha. This shows a very important idea. Microsoft treats the majority of application programmers as end users who do not understand anything and tries to build the largest degree of development friendliness from the api, therefore, it is very strict with the naming method, and the api name is clearly defined. At the same time, it is annoying for various variables and types and is defined multiple times to enable pro

Thanks to the well-known stability and reliability of UNIX operating systems, a large proportion of the operating systems used to provide various Internet services are UNIX and UNIX operating systems, therefore, a large number of people familiar with UNIX operating system applications are required. Common

SCO OpenServer 5.0.5, as a highly efficient and stable multi-user operating system with high security performance, has been widely used in finance, insurance and telecommunication departments. In the daily maintenance work of the system, some system faults are encountered sometimes. The author of the common 10 questions summed up a bit, I hope to be helpful to everyone. First, after powering up the computer, the main console screen appears as follows: Boot not found cannot open stage 1 boot fai

Elk cloner: the first computer virus. It will get all the stuff on your disk, and it will even penetrate into the chip. This is Cloner! It will stick you like glue, and it will modify the memory! DX}Computer viruses are the most famous member of a large number of electronic destructive techniques. They are actually some very dangerous malicious programs, they are ugly, but in my opinion they are cute, derived from my control of the Internet and exploration of computer programs. They will copy th

Unix system security considerations Processes devices into files so that unix programs are independent from devices. That is, programs do not have to understand all the features of the devices they are using, and the access devices do not have to record the length, block size, and transmission speed, network protocols and other such information, all annoying details are concerned by the device driver. To ac