linux if then else

In the shell of Linux The IF statement determines which branch to execute through the relational operator to determine the true or false of an expression. The Shell has three kinds of if ... else statements: If ... fi statement; if ... else .

This article transferred from: http://blog.csdn.net/flowingflying/article/details/5069646　 This article is also the fifth chapter of the Learning the Bash Shell 3rd Edition flow control reading notes, but we will not be limited to this. Flow

#if Else statement, divided into three kinds: if...fi; If ... else ... fi; If ... elif...else...fi#if Else FI statement syntax#if [Expression]#then# Statement to being executed if expression is true#else# Statement to being executed if expression is

In Linux shell programming, in most cases, test commands can be used to test conditions, and here's a simple introduction,For example, comparing strings, judging whether the file exists and whether it is readable, etc., usually uses "[]" to

In Linux shell programming, in most cases, test commands can be used to test the condition, here is a simple introduction, easy to use friendsFor example, comparing strings, judging whether the file exists and whether it is readable, etc., usually

Click Back to learn the path of the Linux command line and shell script12.1-Structured Command If-thenMany programs require some logical process control over the commands in shell scripts. A class of commands will cause the script to skip certain

Beginning Python from Novice to Professional, 2nd Edition, CHAPTER 8, EXCEPTIONS, Page 173: This description in the body: The point was that using try/except statements are in many cases much more natural (more ' pythonic ') than If/else, and you

For example, comparing strings, judging whether the file exists and whether it is readable, etc., usually uses "[]" to represent the condition test.Note: The space here is important. The space to ensure the square brackets. I have wasted a lot of

Process Control statement:The IF statement is formatted as follows:#if语句的后面是Shell命令, if the command performs a successful return of 0, the command following then is executed. The code is as follows Copy Code if

#ifelse_exam. Sh script is used to check whether the input string is a current directory #!/bin/bash# test user input is empty, and then determine if the current directory exists for the file if ["$"]then echo "what are        NOT NULL "if [-E" $ "]