- Testifa given variable is [eq]ual/[n]ot [e]qual/[g]reater [t]han/[l]ess [t]han/[g]reater than or [e]qual/[l]ess than or [e]qual to the specified number: [[$variable-eq|ne|gt|lt|ge|leinteger]] - Testifthe specified variable has a [n]on-empty value: [[ -n$vari...
- Test if a given variable is [eq]ual/[n]ot [e]qual/[g]reater [t]han/[l]ess [t]han/[g]reater than or [e]qual/[l]ess than or [e]qual to the specified number: [[ $variable -eq|ne|gt|lt|ge|le integer ]] - Test if the specified variable has a [n]on-empty value: ...
Use the if-else statement with the -v option to check if an environment variable is set in bash. The echo command in the if block will be executed if the will
Checking If Variable Is Empty in Bash There are multiple ways to check if a variable is empty or not. Before moving towards those methods, knowing when a variable is called empty is necessary. In Bash, a variable is called empty if: A variable is declared without assigning any value to ...
在Bash/Shell脚本中,可以使用特殊字符"\n"来表示换行符。当需要在变量中插入换行符时,可以使用以下方法: 1. 使用双引号(")包裹字符串,并在需要插入换行符的位置使用"\n"。例如: `...
== 等于,如:if [ "a"=="b" ],与=等价 注意:==的功能在[[]]和[]中的行为是不同的,如下: [[ a == z* ]] # 如果a以"z"开头(模式匹配)那么将为true [[ a == "z*" ]] # 如果a等于z*(字符匹配),那么结果为true [ a == z* ] # File globbing 和word splitting将会发生 [ "a" ...
if [ -z ${var+x} ]; then echo "var is unset"; else echo "var is set to '$var'"; fi 参考:https://stackoverflow.com/questions/3601515/how-to-check-if-a-variable-is-set-in-bash 6、换算秒为分钟、小时 代码语言:javascript 代码运行次数:0 运行 AI代码解释 #!/bin/bash a=60100 sw...
How to check if a variable exists or is “null”? How to check if a file exists? How to check if a directory exists? How to check if a command succeeds or failed? How to do string comparison and check if a string equals to a value? How to check if a string is in an array?
{} in array referencesecho"Argument 10 is$10"# Positional parameter misreferenceif$(myfunction);then..;fi# Wrapping commands in $()elseifothercondition;then..# Using 'else if'f;f() {echo"hello world; } # Using function before definition [ false ] # 'false' being true if ( -f ...
echo "Count is zero or negative." fi Example 2: String Comparison !/bin/bash name="Alice" if [ "$name" == "Alice" ] then echo "Hello, Alice!" else echo "You are not Alice." fi Example 3: File Check #!/bin/bash file_path="/path/to/file.txt" ...