CentOS 7 viewing system version and number of digits

Identification standard First of all, we need to know what kind of identity is 32-bit and 64 bit. PC server X86 series I386--I686 are all 32 bits X86 ʄ is 64 bit Order is not too much, in order to prevent the obstacles of selectivity, choose the first method unanimously, the latter is only for supplement. Method 1: [roo ...

Posted on Wed, 08 Jan 2020 13:46:56 -0500 by mediamind

Learn from GCC the implementation of message extension function of C language ﹣ SM3 hash algorithm

According to the standard documents of SM3 hash algorithm, it is easy to write the C language implementation of its message extension function: #include <stdint.h> void expand_data(uint32_t W[68], uint32_t data[16]) { uint32_t j, P1, X; for(j = 0; j < 16; j++) W[j] = data[j]; for(j = 16; j < 68; j++) { X = W[j-16] ...

Posted on Tue, 07 Jan 2020 01:47:27 -0500 by php1999

Change CentOS YUM source to Alibaba cloud software warehouse

It is very convenient for Red Hat Enterprise Linux and CentOS Linux to use YUM installation software. After installing CentOS operating system, if you can use the domestic software warehouse, the speed will be faster. Therefore, we need to modify the configuration file of the YUM source. The suffix of these configuration files is. repo, which i ...

Posted on Sat, 04 Jan 2020 20:48:08 -0500 by gigas10

The first article of the year begins with [Greenplum 6.0] 1 minute installation

Greenplum has iterated several small versions at present in version 6. With the update of the version, bug s are constantly fixed. Friends who are going to try it can start. As the first post of the first working day of the new year, it must start from the "groundbreaking" 6.0. The following content is relatively simple, suitable for ...

Posted on Fri, 03 Jan 2020 11:01:52 -0500 by freddyatlantis

[provide feasibility Script] RHEL 7/CentOS 7/Fedora28 rename network card name

Experiment Description: In many automation tasks, scripts often get information by reading configuration files. After the upgrade of red hat system (CentOS7/RHEL7), the naming method of "consistent network device interface" is adopted for network card naming, resulting in different network card names of different devices. In order to ...

Posted on Tue, 31 Dec 2019 19:33:59 -0500 by akmalsiddique

Online upgrade from CentOS6-x to CentOS7-x (successful! )

Online upgrade from CentOS6-x to CentOS7-x   origin Compared with the Debian Linux distribution (such as Debian and Ubuntu), they can support online large version upgrade very well. The large version upgrade of Red Hat Linux distribution (such as red hat and CentOS) has always been a problem criticized by people. This situa ...

Posted on Fri, 27 Dec 2019 14:11:41 -0500 by jonki

Manage hierarchical data using MySql

Summary We know that relational database tables are better suited for flat lists than for hierarchical data with parent-child relationships that can be directly managed like XML. First, define the hierarchy we are discussing, which is a set of data where each entry can have only one parent and zero or more children (the only exception is the ...

Posted on Tue, 17 Dec 2019 21:15:50 -0500 by Michael Lasky

x007 string and common data structure

String and common data structures Single and double quotes, normal output Three quotation marks, line wrapping output in the middle \Escape Adding r before means no escape s1 = r'\'hello, world!\'' s2 = r'\n\\hello, world!\\\n' print(s1, s2, end='') str1 = 'hello, world!' # Calculate the length of the string through the built-in function le ...

Posted on Mon, 16 Dec 2019 13:21:48 -0500 by tcl4p

String format:%, and. Format

Python 2.6 introduces str.format() Method, its syntax is slightly different from the existing% operator. Which is better and under what circumstances? What's the difference between using each method and having the same result? #!/usr/bin/python sub1 = "python string!" sub2 = "an arg" a = "i am a %s" % sub1 b = "i am a {0}".format(sub1) c ...

Posted on Tue, 10 Dec 2019 09:49:32 -0500 by cocpg

Install resolution Library

Background notes After grabbing the web code, the next step is to get information from the web page. There are many ways to extract information, regular expressions can be used, but it is more cumbersome to write. You can also use a powerful parsing library. In addition, there are very powerful parsing methods, such as Xpath parsing and CSS ...

Posted on Sun, 08 Dec 2019 06:05:16 -0500 by bpgillett