If-statement-Bash-Script-Example if-else Statement 除了普通的 if 语句之外,我们还可以用 else 块扩展 if 语句。基本思想是,如果语句为真,则执行 if 块。如果语句为假,则执行 else 块。 Syntax : if [ condition_command ] then command1 command2 …….. last_command else command1 command2 …….. ...
如果 condition1 成立，那么就执行 if 后边的 statement1；如果 condition1 不成立，那么继续执行 elif，...
'Else if'in bash scripting, often written as'elif', is used to check multiple conditions in your code. It is used with the syntax,if [firstStatement]; then... elif [secondCondition]; then... else. It’s a powerful tool that allows your scripts to make decisions based on various scen...
1. How to use in if condition in shell script? To use an if condition in a shell script, you can follow the basic syntax of an if statement. Here’s an example: if[condition];then# code to execute if condition is truefi For example, to check if a file exists: ...
The words if, then, else, and fi in the preceding script are shell keywords; everything else is a command. This distinction is extremely important because one of the commands is $ 1 = "hi" and the [ character is an actual program on a Unix system, not special shell syntax. (This is...
Syntax <condition> ? <if-true> : <if-false> 三元运算符的行为类似于简化if-else语句。 计算<condition>表达式,并将结果转换为布尔值,以确定接下来应计算哪个分支: 如果<condition>表达式为 true,则执行<if-true>表达式 如果<condition>表达式为 false,则执行<if-false>表达式 ...
善用这个观念,对精简 script 有相当的帮助。 ! 惊叹号(negate or reverse) 通常它代表反逻辑的作用,譬如条件侦测中,用 != 来代表"不等于" 1 2 3 4 5 6 7 8 9 [root@VM_16_9_centos ~]# cat a.sh #!/bin/bash if["$?"!= 0 ];then ...
善用这个观念,对精简 script 有相当的帮助。 ! 惊叹号(negate or reverse) 通常它代表反逻辑的作用,譬如条件侦测中,用 != 来代表"不等于" [root@VM_16_9_centos ~]# cat a.sh #!/bin/bash if [ "$?" != 0 ];then echo "Executes error" ...
1.1 脚本文件的书写格式 (page 1) The standard of Shell script. 1.2 脚本文件的各种执行方式 (page 3) How to run a Shell script. 1.3 如何在脚本文件中实现数据的输入与输出 (page 6) How read and write data through script. 1.4 输入与输出的重定向 (page 17) data redirection. ...
script-file: script-block module-file: script-block interactive-input: script-block data-file: statement-list B.2.2 语句 Syntax 复制 script-block: param-block~opt~ statement-terminators~opt~ script-block-body~opt~ param-block: new-lines~opt~ attribute-list~opt~ new-lines~opt~ param new-...