echo"Now in $dir"elseecho"Can't change to $dir"fi9.test或[]的使用,也不一定要有if 例如 #!/bin/bash var1=20var2=22["$var1"-ne"$var2"] && echo"$var1 is not equal to $var2"home=/home [-d $home ] || echo"$home directory does not exist"注意:&&:前一个操作失败,后一个...
[abc@localhost ~]$ cat nested.sh #!/bin/bash # 这是一个嵌套if else脚本,while循环让用户循环选择字段。 # 定义一个标志 choise=0 # 定义一个函数,打印用户可选择的序号 字段 function p1() { echo "1. BeiJing" echo "2. ShangHai" echo "3. ChangSha" echo "请选择你喜欢城市的序号[1-3]" ...
[ STRING1 > STRING2 ] 如果 “STRING1” sorts after “STRING2” lexicographically in the current locale则为真。 [ ARG1 OP ARG2 ] “OP” is one of -eq, -ne, -lt, -le, -gt or -ge. These arithmetic binary operators return true if “ARG1” is equal to, not equal to, less than,...
if [ $var1 -eq $var2 ] then echo "Variables are equal" else echo "Variables are not equal" fi # Check if a file exists if [ -f $file ] then echo "File exists" else echo "File does not exist" fi # Check if a command is successful ...
TestFile1 does not exist or is empty. 现在创建一个空文件用来测试: [student@studentvm1 testdir]$ File="TestFile1" ; touch $File ; if [ -s $File ] ; then echo "$File exists and contains data." ; else echo "$File does not exist or is empty." ; fi ...
==: Equal to !=: Not equal to -z: Empty string -n: Non-empty string 3. File and Directory Checks: -e: Exists -f: Regular file -d: Directory -r: Readable -w: Writable -x: Executable Example of using If Statement: Let’s illustrate the usage of if statements with a few examples...
在BASH中,if语句用于根据条件执行不同的代码块。if语句可以与or和elif一起使用来增强条件判断的灵活性。 1. if与or语句的区别: - if语句:if语句用于判断一个条件是否为真,...
It is useful when we want to execute a piece of code only if certain conditions meet and execute some when the condition does not meet. The if-else statement is used for this purpose and has several other forms such asif,if-else,if-elif-else,nested if, etc. ...
Optional reading, part 2: Under what conditions does the BASH_SOURCE array variable actually contain multiple elements?: BASH_SOURCE only has multiple entries if function calls are involved, in which case its elements parallel the FUNCNAME array that contains all function names currently on the cal...
Case语句是If语句的一个扩展,它可以让你根据多个条件来执行不同的代码块。例如: case $var in "option1") # code to be executed if var equals option1 ;; "option2") # code to be executed if var equals option2 ;; *) # code to be executed if var does not equal any of the above optio...