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: ...
Shell 支持任意数目的分支，当分支比较多时，可以使用if elif else 结构，它的格式为：ifcondition1then...
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 Copy For example, to check if a file exists: if[-ffile....
1、if语法格式 1.1 if格式 if condition; then commands; fi 1.2 else if 和 else if c...
shell脚本(8)-流程控制if 一、单if语法 1、语法格式: if[ condition ] #condition值为 then commands fi 1. 2. 3. 4. 2、举例: [root@localhost test20210725]# vim document.sh #!/usr/bin/bash #假如没有/tmp/abc这个文件夹,就创建一个if[ ! -d /tmp/abc ]...
The line, if test $1 -gt 0 , test to see if first command line argument($1) is greater than 0. If it is true(0) then test will return 0 and output will printed as 5 number is positive but for -45 argument there is no output because our condition is not true(0) (no -45 ...
--格式如下:if[ condition ]thencommandsfi 第一个方括号之后和第二个方括号之前必须加上一个空格,否则就会报错。test命令可以判断三类条件:(1)数值比较(2)字符串比较(3)文件比较。 1.1 数值比较 下面测试脚本中,第一个条件使用-gt,value1是否大于value2。 第二个条件使用-eq 测试value1 是否与value2相等。
[ condition ] && action; #如果condition条件为真,则执行action; [ condition ] || action; #如果condition条件为假,则执行action; 二、循环控制语句 1、for循环 for var in list; do action; done 其中list可以是一个字符串、序列或数组等。 采用c语言方式的for循环语句: ...
$ if [ $(echo TEST) ]; then echo CONDITION; fi CONDITION Let’s now try the same example without the proper spacing: $ if [ $(echo TEST)]; then echo CONDITION; fi bash: [: missing `]' $ if [$(echo TEST) ]; then echo CONDITION; fi bash: [TEST: command not found $ if [...
If we were to convert the script above to a shell function to includeit in a larger program, we could replace the exit commands with return statementsand get the desired behavior: 类似地,通过带有一个整数参数的 return 命令,shell 函数可以返回一个退出状态。如果我们打算把上面的脚本转变为一个 ...