Article directory
1. Condition test operation
1. test command
Test whether the expression is true, if it is true, return 0, otherwise return other values
Format 1: test conditional expression
Format 2: [conditional expression]
2. File test
[operator file or directory]
3. Commonly used test operators
| symbol | effect |
|---|---|
| -d | Test whether it is a directory (Directory) |
| -e | Test whether a directory or file exists (Exist) |
| -f | Test whether it is a file (File) |
| -r | Test if the current user has 权限读取(Read) |
| -w | Test if the current user 有权限写入(Write) |
| -x | Test if the current user is 有权限执行(excute) |
4. Integer value comparison
[ integer1 operator x- integer2 ]
Common test operators:
| character | effect | symbol |
|---|---|---|
| -eq | Equal to (Equal) | == |
| - is | Not equal to (Not Equal) | != |
| -gt: | Greater Than | > |
| -lt: | Less than (Lesser Than) | < |
| -the: | Less than or equal to (Lesser or Equal) | >= |
| -ge: | greater than or equal to (Greater or Equal) | =< |
2. Logic test
Format 1: [ expression 1 ] operator[ expression]
Format 2: command 1 operator command 2
(1) Method 1
(2) Method 2
(3) Method 3
Commonly used test operators
- -a or &&: logic and, "and" means
- -o or ||: logical or, meaning "or"
- !: logical no
Three. The structure of the if statement
1. Single branch structure
vim test.sh //进入脚本编辑
sh test.sh //进行脚本测试
Enter the script configuration and test
| Experiment: Enter an integer to determine whether it is odd or even |
首先进入脚本书写：
#! /bin/bash
read -p "请输入一个整数：" num
if [ $(($num%2)) -eq 0 ]
then
echo "$sum是偶数"
else
echo "$sum是奇数"
fi
然后进入测试：
2. Double branch structure
| Experiment: Prompt the user to enter the number of seconds for the 100-meter race. It is required to judge that the number of seconds is greater than 0 and less than or equal to 10 seconds to enter the trial, and those greater than 10 seconds will be eliminated. If you enter other characters, you will be prompted to re-enter; members who enter the trial will make further judgments Male and female gender, boys enter the boys group, girls enter the girls group, if the input is wrong, please prompt the error |
Four. case statement structure
case多分支结构
格式：
case 变量名称 in
模式1）
命令序列
；；
模式2）
程序段
；；
*）
不包含第一个变量内容与第二个变量内容的其他程序执行段
默认程序段
；；
esac
| Experiment: Use the case statement to decompress the compressed package named .tar.gz or tar.bz2 according to the suffix to the /opt directory |
进入脚本书写：
进行脚本测试看是否能被解压
