if [ "$a" == "a" ]; then b="b1" else b="b2" fi # or one-line syntax if [ "$a" == "a" ]; then b="b1"; else b="b2"; fi 用case语句: case "$a" in a) b="b1" ;; *) a="b2" ;; esac 在bash里面可以这么用 [condition]&&variable=value_if_true||variable=value_...
Bash条件判断(condition-test)是用来控制程序的流程,它可以添加一些条件,根据不同的条件做出不同的反应。Bash条件判断中一般可以分为:条件测试算式、条件操作符、逻辑操作符;其中单词语法(word-based syntax)是Bash条件判断的基础;即使用if,test等命令用来判断条件。 条件测试算式 条件测试算式是Bash条件判断的基础,它将...
Conditions in bash scripting (if statements) - Linux Academy Blog https://linuxacademy.com/blog/linux/conditions-in-bash-scripting-if-statements/ Table of conditions The following table list the condition possibilities for both the single- and the double-bracket syntax. Save a single exception, th...
因为if condition,如果条件为真,就会进入if块区域内执行命令。 如果你是对$?结果很执着的读者,可以去看朱双印的博客原文。 场景一:判断变量是否为空 假如有变量 如上表所示,变量值非空时 condition 为真。使用上述方法判断变量值是否为空时,[ ] 与 [[ ]] 没有区别。 我们可以使用”!”进行取反,使得变量值...
'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...
A basic if statement commands that if a particular condition is true, then only execute a given set of actions. If it is not true, then do not execute those actions. If statement is based on the following format: Syntax of If statement ...
我只是试着运行一个简单的bash脚本,它就是不能工作。整个脚本是这样的:/home/pi/akr2.exesh: 1: Syntax error: "(" unexpected sh: 1: Syntax error:/script.sh还是bash script.sh运行<e 浏览1提问于2014-11-21得票数 0 1回答 使用linux "at“函数运行docker命令 、 我正在运行一个PySpark脚本,该脚...
]; then echo "JAIL is set to a non-empty string"fiif [ -n "${JAIL+set}" ]; then echo "JAIL is set, possibly to the empty string"fiif [ -n "${JAIL-unset}" ]; then echo "JAIL is either unset or set to a non-empty string"fidone## syntax 1 ##if [[ -z "$va...
if[condition];thencommandelif[condition];thencommandelsecommandfi 当然,与其他语言一样,else和elif都可以选择性地去掉。但是结尾一定记得要加fi。 命令行参数 之前已经接触到了$1这种表示参数位置的变量。其实还有其他的相关变量可以使用。最常用的为:
We can easily understand the syntax of a bash ‘if statement’ as with a normal programming language. The only difference is that we should use the ‘fi’ keyword to indicate the end of the conditionals. So, let’s try the following bash script. #!/bin/bash echo if then else ...