learning bash shell amazon

processed by NF￥0 Select Entire row￥1 first Column￥NF last ColumnAwk-f: ' {print nr,￥1,￥2} '/etc/passwordTo: Print out the contents of the first and second columns as separatorsAwk-f: ' {print nr,￥1,￥nf} '/etc/passwordPrint out the first and last columns-----------------------------------------------------Scripting specifications#！ /bin/bash#注释BodyScript Execution Permissionschmod u+x hello.sh #u指users, x means execute permission./hello.shLocal varia

Common shell script interpreters in Unix/Linux include bash, sh, CSH, and KSh. Bash is the most common interpreter in Linux. Script Language isInterpreted languageWhen executing such programs, the interpreter (Interpreter) needs to read the source code written by us, convert it into the target code (object code), and then run it on the computer. The common C, C +

"$number"]//The less-than number here is-LT Note! DoI=$ (($i +1) //Why do we need two () here? Because () there is the meaning of the operation S=$ (($s +$i)) DoneEcho-E"the result of ' 1+2+...+ $number ' is: $s" You can try Echo (1+2) is not out of 3, and Echo ((1+2) will come out 3, so () have a whole operation meaningUntile do-done conditions don't fit in.For...do...done here is the first use of#!/bin/bashs=0for ((i=1; i, i++)) do s=$ (($s +$i))doneecho $sF

also has built-in variables. The function name represents $0, and the subsequent variables are also $1, $2... [[Email protected] Scripts] # vi sh12-3.sh #! /Bin/bash # program: # use function to repeat information. # History: #2005/08/29 vbirdfirst releasepath =/bin:/sbin:/usr/bin:/usr/sbin:/usr/local/bin:/usr/local/sbin :~ /Binexport pathfunction printit () {echo "your choice is $1" # This $1 must be issued by referring to the following com

Key Points:shell types, echo,$, basic syntax, Ls,man,su,sudo,grep,ps,clear,cp,rm,cat,moreReference: http://www.jb51.net/LINUXjishu/45329.htmlThere are many types of shells, such as the Csh,bourne Shell,korn shell. In most Linux distributions today, the default shell is typically the Bourne Again Shell (

First, shell overview1.Shell Overview:Shell: Shell, a shell is a command-line interpreter that provides users with an interface-level program that sends requests to the Linux kernel to run programs, and users can start, suspend, stop, or even write programs with the shell. S

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 here as notes.===============linux Shell Introduction ================

[This is my own study notes, welcome reprint, but please specify the source:http://blog.csdn.net/jesson20121020] Shell Script basic elements:#!/bin/bash ---First line # ---comment variable flow control structureLook at a simple example, learn any language, I think most of the cases are starting from the HelloWorld program, the shell is a language, we

is a weakly typed variable that does not need to specify its variable type when declaring it, and does not need to follow the "declare before use" and can be used whenever you want. A variable in which a local variable is in effect in a shell is not valid in another shell. You can use the local built-in command to "display" the declared local variables in the environment variable

Getopts is a bash shell built-in command that parses a command-line pass in a shell script, passes it to a function, or passes it to a shell script that is passed to another call (option or parameter, which is explained later, getopts only supports short options, To resolve the long option, refer to getopt).getopts com

enter a variable value to the variable name at the keyboardIf you read+ multiple variable names, separate the values of the input variables with a space.More useful Commands read-p "Please input xxxxx:" + variable nameThe scope of the The export variable name can declare a variable as a global variable (this variable can be used in a child shell)be able to export XX = xxx at the time of definitionUse the unset variable name to eliminateOperation of C

Use of shell Learning () and {}In shell command line, the average person may not care much about the differences between the two pairs of symbols () and,Although both of them can group multiple commands, the technical details are quite different:() Place the command group in sub-shell for execution, also known as neste

/Egrep = Grep-eSED basic usage of Shell:Sed ' p-n 1.txt: Plus-n prints out rows that match the rulesSed-n '/root/' p 1.txt: Print lines that contain special characters-r:sed does not recognize +| Symbols such as {} () need to be de-defined characters \ or-RSed-n-R '/ro+/' P 1.txtSed-n '/ro\+/' P 1.txt-E: Implementation of multiple tasks, can also be used; To achieveSed-e '/root/p '-e '/body/p '-n 1.txtD: Delete the specified lineSed '/root/d ' 1.txt; Sed ' 1d ' 1.txt; Sed ' 1,10d ' 1.txtS: repla

://s3.51cto.com/wyfs02/M02/4D/96/wKioL1RURCHD46UKAAFTBMQxVAk699.jpg "title=" aa.jpg "alt=" Wkiol1rurchd46ukaaftbmqxvak699.jpg "/>Single quotes, cannot interpret other variables, all the contents of the single quotation mark are output as-is.There is no demo here.Anti-apostrophe: The content output of the "inside" is mainly displayed.650) this.width=650; "src=" http://s3.51cto.com/wyfs02/M00/4D/97/wKiom1RURR3RPi47AAGCG0hsPIs298.jpg "title=" aa.jpg "alt=" Wkiom1rurr3rpi47aagcg0hspis298.jpg "/>Read

addition to the-N options, has the following common choices:7-E: Activate the inverse of the control character conversion (refer to the following table)-e: Close the inverse of the control character conversion (this is the case)-N: Cancel line end of the line symbol (with the-e option under the \c character consent)The following table lists the anti-skew control characters supported by the echo command:\a:alert/bell (from the system speaker)\b:backspace, that is, to the left to remove keys\c: C

echo0The first echo in the above example is about the RV of ls my. file. The value of 0 can be obtained, so it is true;The second ECHO is about the RV of ls no. file. A non-0 value is obtained, so it is false; The third ECHO is about the second echo $? Is 0, so it is true. However, there is a command dedicated to test a condition and send return value for true or falseJudgment,It is the test command!If you are using bash, enter man test or man

1, the variables in the shell can be customized, the shell uses the variable with the $Name= "Shero"echo "Hi ${name}"[Email protected]:/home/shero/shell#./test2.shHi SheroNote that there can be no spaces between the variable name and the equals sign, which may be different from any programming language you are familiar with. At the same time, the name of the vari

the variables, the unset var command clears the variable Var,var equivalent to not defined. readonly var can change Var to a read-only variable, and you cannot make any changes to Var after the definition. There are many references to shell variables, which can easily be used to get the value of the shell variable, the length of the variable value, a string of variables, the value of the variable being par

generated file to $ Umask 000, which is changed to 000, and the specific rules refer to the table above.In fact, the value of Umask is set in/etc/profile this configuration file, for a specific user, you can set their own umask in $home/.profile or $home/.bash_profile1.7. Symbolic Link, LnHard links, $ ln resource destinationSoft links, $ ln-s resource destination1.8. Learn the yuanyin of shell scriptsShell scripting is powerful, for example, for a

Tags: set existence function budget util tag file contains something CTI20171123 Linux Shell Basics Learning Notes1. The beginning of the shellGenerally #!/bin/bash through the #! To uniquely specify the shell path to useThe other # all represents comments.2. Shell variables