In bash scripting, if conditions are used to control the flow of execution based on certain conditions. Logical operators play a important role in constructing these conditions. There are several logical operators available in bash scripting that can be used in if conditions. These operators allow us to combine multiple conditions and evaluate them as a single expression. The logical operators in bash scripting are as follows:
1. AND Operator (`&&`): The AND operator evaluates two conditions and returns true if both conditions are true. Otherwise, it returns false. This operator is represented by `&&` in bash scripting.
Example:
if [ condition1 ] && [ condition2 ] then # code to be executed if both conditions are true else # code to be executed if either of the conditions is false fi
2. OR Operator (`||`): The OR operator evaluates two conditions and returns true if at least one of the conditions is true. It returns false only if both conditions are false. In bash scripting, the OR operator is represented by `||`.
Example:
if [ condition1 ] || [ condition2 ] then # code to be executed if either of the conditions is true else # code to be executed if both conditions are false fi
3. NOT Operator (`!`): The NOT operator negates the result of a condition. It returns true if the condition is false and vice versa. In bash scripting, the NOT operator is represented by `!`.
Example:
if ! [ condition ] then # code to be executed if the condition is false else # code to be executed if the condition is true fi
These logical operators can be combined to form complex conditions in if statements. Parentheses can also be used to group conditions and control the order of evaluation.
Example:
if [ condition1 ] && ([ condition2 ] || [ condition3 ]) then # code to be executed if condition1 is true and either condition2 or condition3 is true else # code to be executed if the condition is false fi
It is important to note that the logical operators in bash scripting operate on exit codes. The `[` command is used to evaluate conditions, and it returns an exit code of 0 (true) or 1 (false) based on the result of the condition. The logical operators then combine these exit codes to determine the final result.
The logical operators (`&&`, `||`, `!`) in bash scripting are used in if conditions to combine and evaluate multiple conditions. They allow us to control the flow of execution based on the outcome of these conditions.
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