或:bash conditional-statements logical-operators 1个回答 51投票 if [[ ! ($var == 2 || $var == 30 || $var == 50) ]] ; then do something fi 一个好的做法是在您的条件操作员和操作数之间拥有空间。 也可能建议,如果您只是比较数字,改用算术运算符,或者只是使用(( )) :: if ! [...
Pay special attention to space. There must be space between the opening and closing brackets and the conditions. Similarly, space must be before and after the conditional operators (-le, == etc). Here's what it shows when I run the script: Did you notice that the script tells you when ...
Conditional statements are a fundamental part of any programming language, and bash scripting is no exception. They allow your scripts to make decisions based on certain conditions. The basic conditional statements in bash are ‘if’, ‘else’, and ‘elif’ (else if). Here’s a basic ‘if’...
Unary operators are often used to test the status of a file, a variable, a shell option (optname), or a string. Unary and Binary expressions are formed with the following primaries. Conditional ExpressionMeaning -a file True if file exists....
There must be space before and after the conditional operator (=, ==, <= etc). Otherwise, you'll see an error like "unary operator expected". Now, let's create an example scriptroot.sh.This script will echo the statement “you are root” only if you run the script as the root use...
Knowing how conditionals work in bash open up a world of scripting possibilities. We’ll learn the basic syntax, including if, else, and elif. Then we'll look at a few of the "primary" operators you can leverage in a conditional statement such as = for string equality, -eq for numeric...
if [ "$string_variable" = "desired_value" ]; then # Code for when the string variable is equal to "desired_value" else # Code for when the string variable is not equal to "desired_value" fi Q. What are the basic Bash commands used in conditional statements?
Conditional Constructs/GNU 拖入浏览器,方可跳转到指定锚点https://www.gnu.org/software/bash/manual/bash.html#:~:text=%5D-,3.2.5.2%20Conditional%20Constructs,-if Shell 中test单中括号[\] 双中括号[[]] test/[ ]判断 Linux test Command Tutorial for Beginners (with Examples) (howtoforge.com) ...
if [ expression ]; then statements elif [ expression ]; then statements else statements fi the elif (else if) and else sections are optional Put spaces after [ and before ], and around the operators and operands. Expressions An expression can be: String comparison, Numeric comparison, File ...
Under Logical operators, Bash provides logical OR operator that performs boolean OR operation. Bash boolean OR operator takes two operands and returns true if any of the operands is true, else it returns false. OR logical operator combines two or more simple or compound conditions and forms a ...