NAME
    [[ ... ]] - Execute conditional command.

SYNOPSIS
    [[ expression ]]

DESCRIPTION
    Execute conditional command.
    
    Returns a status of 0 or 1 depending on the evaluation of the conditional
    expression EXPRESSION.  Expressions are composed of the same primaries used
    by the `test' builtin, and may be combined using the following operators:
    
      ( EXPRESSION )	Returns the value of EXPRESSION
      ! EXPRESSION		True if EXPRESSION is false; else false
      EXPR1 && EXPR2	True if both EXPR1 and EXPR2 are true; else false
      EXPR1 || EXPR2	True if either EXPR1 or EXPR2 is true; else false
    
    When the `==' and `!=' operators are used, the string to the right of
    the operator is used as a pattern and pattern matching is performed.
    When the `=~' operator is used, the string to the right of the operator
    is matched as a regular expression.
    
    The && and || operators do not evaluate EXPR2 if EXPR1 is sufficient to
    determine the expression's value.
    
    Exit Status:
    0 or 1 depending on value of EXPRESSION.

SEE ALSO
    bash(1)

IMPLEMENTATION
    GNU bash, version 5.0.17(1)-release (x86_64-redhat-linux-gnu)
    Copyright (C) 2019 Free Software Foundation, Inc.
    License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html>