Unix If Statement

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 ...

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: ...

This paper introduces how to build a network database application method by MySQL of the golden combination of Web database, PHP is a server-side embedded hypertext Processing language similar to Microsoft ASP, it is a powerful tool to build dynamic website. While MySQL is a lightweight SQL database server that runs on a variety of platforms, including Windows NT and Linux, and has a GPL version, MySQL is considered the best product for building a database-driven dynamic Web site. PHP, MySQL, and Apache are Linux ...

For years, the server market, which has formed a more stable competitive landscape, has been a sleepy one-except that you see IBM and Hewlett-Packard taking turns as "Big Brother" and Dale and Fujitsu scrambling for the third fourth, there's hardly anything new. However, the past 2011, but can let the observer in the server field for the spirit of a vibration, because, if only one keyword to describe the 2011-year server market, it must be: "Change." 　　As for "Change" where, and let the author one by one. 2011: The undercurrent of dance under the surging from the entire server market industry ...

We say that the main purpose of program debugging is to observe variable changes. But if the program keeps running until it stops or fails, there will be no chance to observe any variables. Therefore, how to effectively control the execution of the statements in the program, so that when the appropriate time to pause, the debugger to display or set the value of some of the storage unit and then continue from where to stop, is the debugger should have a basic function. In this section we will specifically describe how to control the operation of the program. The first problem with program execution control is to set breakpoints. A breakpoint ...

Mac OS is the operating system that runs on Apple's Macintosh family of computers, and has been used by the industry to compare with Microsoft's Windows. Mac OS is the first commercially successful graphical user interface, when Mac OS launched a graphical interface, Microsoft remained in the DOS era, Windows is still in swaddling. 　　As Mac OS X Lion is about to launch, let's review the Mac OS's "Past and Present life". Mac OS can be divided into two of the operating system ...

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.

In the past, we have introduced some principles of software development, such as the 10 commandments of high quality code and the UNIX design principles described in the UNIX legend (next article). I believe that you can learn from middle school some knowledge of design principles, as I said in the "How Do I Recruit procedures", a good programmer usually consists of its operational skills, knowledge level, experience level and ability four aspects. Here I would like to talk about some of the principles of design, I think these things belong to the long-term experience summed up knowledge. These principles should be understood by every programmer. But...

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 ...

MySQL has become one of the most widely used databases in the current network, especially in Web applications, which occupy the absolute advantage of small and medium applications. It all stems from its compact, safe, efficient, open licensing and multi-platform, and, more important, the perfect combination of--php with one of the three web languages. Unfortunately, a default installation of MySQL, because the root password is empty and the program vulnerabilities caused by the overflow, so that the installation of MySQL server is a frequent target. What is more serious is that the database is often destroyed after the attack, causing disaster easily ...