9-shell Logical operator Knowledge Introduction-Practice and Enterprise case script anatomy

logical operators

logical operators used in [] and test	logical operators used in [[]]	Description
-A	&&	And and, both ends are true, then true
-O	||	Or OR, at both ends there is a true and true
!	!	Not non, the opposite is true

Tips:

！ Inverse: A logical value that is opposite to a logical value

-A Chinese meaning and (and &&): Two logical values are true, the return value is true, and the reverse is false

-O Chinese meaning yes or (or| | ): Two logical values if one is true, the return value is True

Example:

[[Email protected] ~]# [$a-eq 2-a $b-eq 2]&&echo 1| | echo 00[[email protected] ~]# [$a-eq 2-o $b-eq 2]&&echo 1| | Echo 0 1

Summary:

[] with-a,-o

[[]] with &,| |,!

Test usage and [] same

multiple [] and multiple [[]], or arbitrary or mediation logic operations are && or | |

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9-shell Logical operator Knowledge Introduction-Practice and Enterprise case script anatomy