- Test if the specified variable has a [n]on-empty value: [[ -n $variable ]] - Test if the specified variable has an empty value: [[ -z $variable ]] - Test if the specified [f]ile exists: [[ -f path/to/file ]] - Test if the specified [d]irectory exists: [[ -d path/...
在Bash中,可以使用条件语句来检查变量是否在范围内。 要检查变量是否在范围内,可以使用if语句结合比较运算符和逻辑运算符来实现。下面是一个示例代码: 代码语言:txt 复制 #!/bin/bash # 定义范围的上下限 lower_limit=10 upper_limit=20 # 要检查的变量 num=15 # 使用if语句检查变量是否在范围内 if [[ $nu...
- Testifthe specified variable has a [n]on-empty value: [[ -n$variable]] - Testifthe specified variable has an empty value: [[ -z$variable]] - Testifthe specified [f]ile exists: [[ -f path/to/file ]] - Testifthe specified [d]irectory exists: [[ -d path/to/directory ]] ...
In Bash (at least as far back as 3.0), if var is a declared/set variable, then declare -p var outputs a declare command that would set variable var to whatever its current type and value are, and returns status code 0 (success). If var is undeclared, then declare -p var outputs ...
Unary operators are often used to test the status of a file, a variable, a shell option (optname), or a string. Unary and Binary expressions are formed with the following primaries. Conditional ExpressionMeaning -a file True if file exists....
file="/test.sh" # 由于没有给出条件,所以返回true if [ ! ] then echo "File exists" else echo "File not exists" fi 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 流程控制 if else 语法格式: if condition1 then command1 elif condition2 ...
if [ ! -e /tmp/test10 ]; then mkdir /tmp/test10 fi 五、bash变量类型 局部变量 本地变量 环境变量 位置变量 特殊变量: $?:用于保存刚刚执行的命令的状态返回值; 0:成功执行; 1-255:表示执行失败,1、2、127这3个返回值默认被系统占用,可以使用exit命令在脚本中自定义脚本执行状态返回值;如果不定义,...
TestFile1 does not exist or is empty. 现在创建一个空文件用来测试: [student@studentvm1 testdir]$ File="TestFile1" ; touch $File ; if [ -s $File ] ; then echo "$File exists and contains data." ; else echo "$File does not exist or is empty." ; fi ...
21. Test if File Exists In order to check if a given file exists, users can perform conditional tests. In this case, we’ll useanifstatement with a-fflag. The flag checks if a given file exists and is a regular file. Start by creating the script file: ...
持续集成和交付（CI / CD）管道旨在支持每天数以万计的部署。生产部署的频率不能以牺牲安全为代价，...