Shell If Syntax

The Linux shell refers to a program that allows users to manipulate computers by typing instructions to the keyboard. The shell executes http://www.aliyun.com/zixun/aggregation/18678.html > user-entered commands and displays the execution results on the monitor. The whole process of this interaction is text-based and differs from the graphical operations described in other chapters. This command-line-oriented user interface is called the CLI (command line ...).

By completing this chapter, you will be able to do the following: Describes the effect of a return value in a conditional branch statement. Use the test command to parse the return value of a command. Use the IF and case structures in a shell program. &http://www.aliyun.com/zixun/aggregation/37954.html ">nbsp;1. Return value shell variable"? "To save the return value of the last executed command: 0: ...

By completing this chapter, you will be able to do the following: Use the while statement to repeatedly execute a piece of code when the condition is true. Use the loop statement to repeatedly execute a piece of code until the condition is true. Use the interactive for statement for loop control. 1. Brief introduction to the loop objective: Repeat the execution of a list of commands. control; a return value based on a key command. Three forms: While ... do ... do loop ... do ... do.

The friendly interactive shell, just like its name, fish is a very friendly shell, highly recommended! Use the command sudo apt install fish to install it. When you are done, run the command fish to switch to fish and exit back to bash. A brief introduction to its advantages: automatic completion, syntax highlighting the automatic completion of bash is only the completion of the full command, the path, if you want to complement the full variable, parameters, etc., usually need to use complex combination ...

The 7.for statement loops through each entry in the list, giving Var the next entry in the list each time the loop completes, until the end of the last entry is completed. Syntax: example: for VAR in list $ cat Test_fordo For X in 1 2 3 4 5 list A Dodone ...

8.if statement syntax: (for one-way Judgment branch) if list A then list B fi Example: if Test-s funfile then echo funfile exists fi echo Hello if structure is a value based on command return Process Control mode. If the test command returns a value of 0, a specified list of commands is executed, and if the command returned with a value other than 0, the specified command list is ignored ...

-----------------------20080827-------------------insight into Hadoop http://www.blogjava.net/killme2008/archive/2008/06 /05/206043.html first, premise and design goal 1, hardware error is the normal, rather than exceptional conditions, HDFs may be composed of hundreds of servers, any one component may have been invalidated, so error detection ...

&http://www.aliyun.com/zixun/aggregation/37954.html ">nbsp; The Windows PowerShell command prompt is a language that supports objects, and we can simply assign the result returned by the command to a variable, $files contains a collection of objects in the table of contents that are in the previous directory, and use the normal array access syntax to get the object at that location ....

This article is written by http://www.aliyun.com/zixun/aggregation/13357.html ">azure CAT team Piyush Ranjan (MSFT). As infrastructure services (virtual machines and virtual networks) are recently officially released on Windows Azure, more and more enterprise workloads are migrating to the public cloud to take advantage of cloud profitability, scale, and speed. I recently participated in one of the enterprise work negative ...

Intermediary transaction SEO diagnose Taobao guest Cloud host technology Lobby database optimization is a very complex task, because it ultimately requires a good understanding of system optimization. 　　Even though the system or application system does not know much about the optimization effect is good, but if you want to optimize the effect of better, then you need to know more about it. 1, the optimization of the system to run faster the most important factor is the basic design of the database. 　　And you have to be aware of what your system is going to do, and the bottlenecks that exist. The most common system bottlenecks are as follows: ...