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brother Author Blog address: HTTP://BLOG.CSDN.NET/LFDFHL SQL BriefStructure Query Language (Structured Query language) is referred to as SQL, which is defined by the U.S. National Standards Office (ANSI) as the United States standard for relational database languages, and then adopted by the International Standards Organization (ISO) as the international standard for relational database languages. Database management system can manage databa

Linux is a file, bird brother called the archives. Since it's a file, the file has the following features.1. User of the file2. Permissions of the file3. Types of Archives1. User of the fileFiles can be managed, modified, and queried by people of different roles. Roles are divided into the following three types1. Owner of the file: User2. Group: Group3. Other: OthersRoot user has the overriding privileges2. Permissions of the fileFiles can be divided

"Brother worked every day, the 40th article"Why take this title? Because yesterday, some would have "support" for the brother to see the brother to pay VIP group, feel that the money is not moral to make a brother to earn bitter developers, say then to seek elder brother I w

1.1 Linux is what 1.1.1 Linux isLinux is a set of operating systems-an environment in which programmers can develop software more easily1.1.2-1.2.4 (omitted on Linux predecessor, GNU Project, and Torvalds Linux development process)Kernel version of 1.2.5 Linux The main and minor versions are odd in the developing version The primary and minor versions are even stable versions 1.2.6 Linux DistributionsFully-installable Linux Publishing SuiteMajor similarities and differences bet

a Linux system, in order to speed up the reading speed of the data, some data will not be written directly to the hard disk in a preset situation.Instead, the memory is present, so that if a data is rewritten by you repeatedly, because he has not yet been written to the hard disk,Can be read directly from memory, in the speed must be very fast on quite a lot!However, this is also a bit of a problem, that is, in case you reboot, or shutdown, or an abnormal power loss of the situationThe data has

First, command aliases:Alias cmdalias= ' COMMAND [options] [arguments] 'Example: Alias Cls=clearNote: Aliases defined in the shell are valid only for the current shell life cycle, and the valid range of aliases is only the current shell process.Alias: Unalias ComaliasSecond, the command to replace:Replaces a subcommand in a command with the process of executing the result.$ (command), anti-quote: ' COMMAND 'Example: File-2016-12-05-10-21-33.txeTouch./file-$ (date%f-%h-%m-%s). txtThird, bash-supp

above functions;2>: Redirect Error output2>>: Append mode redirect Error output>: Redirect standard output or error output to the same file2. Input redirection:Iv. Pipeline:The output of the previous command, as input to the latter commandExample: 1. Display the number of rows in a file does not display the file nameWc-l/etc/passwd | Cut-d '-f12. Count the number of files in the/usr/bin directory;Ls/usr/bin | Wc-l3. Remove all shells from the current user, requiring each shell to be displayed o

First, view the text:Cat: Connect and Show TAC: Reverse display of text content-N: Show line numbers-E: Displays the line terminator for each lineNote: For Linux systems, the line terminator for each line of the text file is $. The Windows system has two terminator: $ and line breaks.Second, split screen display:MORE: Only support backward, turn to the last screen exit.Less: Same as manSPACE:B:ENTER:K:Third, head, tailHead-n View Top N rowsTail-n: View after n rows-F: Look at the end of the file

time-I: Inactive time-M: Minimum period of use-M: Maximum lifespan-W: Warning timePractice: Create a user Mandriva with an ID number of 2002, a base group of distro (group ID 3003), and an additional group of Linux #:groupadd-g 3003 distro#:groupadd Linux#:useradd-u 2002-g distro-g Linux Mandriva2. Create a user fedora with the full name of Fedora Community, the default shell is tcsh#:useradd-c "Fedora Community"-s/bin/tcsh Fedora3. Modify Mandriva with ID 4004, Basic Group Linux,

shut down.2) Run Level 3: pure command line mode.3) Run Level 5: Contains graphical interface mode.4) Run Level 6: Reboot.6. Troubleshooting problems with the boot processFirst, the problem of file system error is discussed. There are three scenarios: the root directory is not corrupted, the root directory is corrupted, and the hard disk is broken.Finally, we talked about forgetting the root password . Describes the use of the Grub boot loader to resolve this issue. Copyright NOTICE: This artic

, = representative settings.File or directoryEg1:infor Original permission is drw-r–r– input command chmod u=rwx,g=rw,x=rx inforInfor Permissions to Drwxrw-r-x (note that there is no space in the middle of the U=rwx,g=rw,x=rx)Eg2:infor Original permission is drw-r–r– input command chmod u-w inforInfor Permissions Change to dr–r–r–5. Copy files: CP source file Target file EG:CP. bashrc. bashrc_testsecond, log in rootMethod 1: Enter the command: sudo su then prompts to enter the current account (S

database to find files, so it's fairly fast . The Linux operating system records all the file information in a database file, and the Whereis and locate commands are used to locate the file using this database file. Although this approach is fairly fast, the database file update is not real-time (different distribution, CentOS updates the data file once a day), so when you use the Whereis or locate command to find a file You may have found a file that has been deleted, or the newly created file

database file, and the Whereis to use the locate is the next to say that the contents of the database will be based on the content, therefore, you will find the use of these two files, you will find the file has been killed! And Hideaway also can't find the latest files that have just been created! This is because the two led orders are the result of database bi search for files! Locate is related to the Linux archive database (the Linux system will keep all of the files in the system 弽 in a d

/munin/munin-node.confExample:Allow ^127\.0\.0\.1$Allow ^10\.10\.20\.20$# What address does the supervisor hearHost *# and which portPort 4949Note: 10.10.20.20 is my Munin server, which connects to the client's 4949 port to get the data.Step 3Restart The Munin-node in the client machine :Service Munin-node RestartTest connectionCheck if you can connect from the server to the client's port 4949, and if not, you need to open the port on the firewall in the client machine.Telnet db.linuxnix.com 494

shutting down or restarting, always)Although the current Shutdown/reboot/halt and so on led order are already in the shutdown before Import line sync This tool call, but do more than a few times more comfortableShutdown)To learn how to use the method, man shutdownCommand:/sbin/shutdown-h ' I'll shutdown after ten mins 'Time is the parameter that must be added, otherwise shutdown will automatically jump to run-level 1 as a maintenance log-in situationExample: Shutdown-h now shuts downShutdown-h

/locale.gen # # # Output Locale.gen content$ cat-n/etc/locale.gen # # # Output Locale.gen content and display line numbersMoreMuch like cat, you can view the contents of a file, except that when a document is too long, cat can only show the last content that is covered by the screen, and the front content is not visible. This is where you can display content more than once.$ more/etc/locale.gen$ More +100/etc/locale.gen # # # Starting from 100 lines displayLessLess is similar to more, but less s

1. Find the file size from 50KB to 60KB under/etc, and list the permissions in fullThe answer is Find/etc-size +50k-size-60k-exec ls-l {} \;or write find/etc \ (-size +50k-and-size-60k \)-exec ls-l {} \;2. Find the file size greater than 50KB and the file owner is not the root file name, and the permissions are fully listedThe answer is Find/etc-size +50k! -user root-exec ls-l {} \;Here! For the "non" decision, which means that if the back is true, the output3. Find files with capacity greater t

1. Pre-reptile analysisBecause to realize the translation function of Youdao translation, it is necessary to find its interface, open the review element, go to the Network Listening window (NET), view API interface.See how the salt and sign are generated by viewing the source code of the Web page to view the translated JS file. View Web page source code find JS file Find the JS file, then click on this file, jump to this source file, then select all the code, copy it down

File name, compressed files using gzip in Windows system, can be decompressed with WinRARPackage Command Tar①windows's winrar also supports decompression of tar.gz filenames② parameter:-j Compression/decompression via BZIP2 support-Z Compression/decompression via GZIP support-P Save the permissions and properties of the original file③ View data contents of tar ' File: Tar-jtv-f/root/etc/tar/bz2④ Unpacking: Tar-JXV-f/root/etc/tar/bz2⑤ only unlocks a single file: Tar-jtv-f/root/etc/tar/bz2 | grep

. BZIP2 compression efficiency is better than gzip. Instruction is bzip2-z man.config, direct read is Bzcat man.config.bz2, unzip to bzip2-d man.config.bz25. Tar can combine multiple packages into a single file, and also can compress files simultaneously through GZIP/BZIP2 support, in fact, the WinRAR function of Windows also supports. tar.gz file name decompression. The decompression instructions for tar are tar-jxvf/root/etc.tar.bz2.6. The main role of the dump command is to back up the entire