-bash: conditional binary operator expected -bash: syntax error near `1' [root@adminset 06]# [[ ! -n "$a" && "$a" = "$b" ]] && echo 1 || echo 0 0 [root@adminset 06]# [[ -z "$a" || "$a" != "$b" ]] && echo 1 || echo 0 1 [root@adminset 06]# [root@admin...
例如在[ ... ]中可以用引号括起操作符,因为在做命令行扩展时会去掉这些引号,而在[[ ... ]]则不允许这样做 user@ae01:~$ ["-z"""]&&echotrue||echofalsetrue user@ae01:~$ [["-z"""]]&&echotrue||echofalse-bash: conditional binaryoperatorexpected-bash: syntax error near `""' 算术扩展 [[...
bash: conditional binary operator expected bash: syntax error near `""' $ [[ -z "" ]]&&echo true||echo false true 4.3` `.``.``.` `进行算术扩展,而[ ... ]不做 $ [[ 99+1 -eq 100 ]]&&echo true||echo false true $ [ 99+1 -eq 100 ]&&echo true||echo false bash: [: 9...
$ [[ 1=1]] &&echoTrue bash: conditional binary operator expected bash: syntax error near `True' So, we must pay a little attention when we construct our sentences. 6. Conclusion In this article, we’ve covered conditional expression and how we can build expressions using different constructs...
[: file: binary operator expected 再来看看glob expansion $ touch '*' $ (foo="*";[ -f $foo ]&&echo "$foo is a file") #为什么显示too many arguments,因为 *被扩展为所有目录下的文件 bash: [: too many arguments $ (foo="*";[[ -f $foo ]]&&echo "$foo is a file") # *被当成...
bash: [: file: binary operator expected 再来看看glob expansion $ touch '*' $ (foo="*";[ -f $foo ]&&echo "$foo is a file") #为什么显示too many arguments,因为 *被扩展为所有目录下的文件 bash: [: too many arguments $ (foo="*";[[ -f $foo ]]&&echo "$foo is a file") # ...
Boolean contexts - PowerShell converts the conditional expressions of if, while, do, or switch statements to Boolean values, as previously described. For more information, see about_Booleans. Extended Type System (ETS) type definitions - Type conversions can be defined in several ways: Using ...
A null conditional operator permits member access,?., or element access,?[], to its operand only if that operand evaluates to non-null; otherwise, it returns null. Note Since PowerShell allows?to be part of the variable name, formal specification of the variable name is required for using...
In the conditional judgment instruction if, you can directly take a string type of fast expression, which is convenient for code writing.- 灵活表达式(Flex expression)谢语言还支持接近其他语言中的语法的表达式,称作“灵活表达式”(Flex Expression),使用flexEval或flexEvalMap指令进行运算,具体用法请参看下面...
attribute_type := NUMBER|STRING|BINARY primary_key := PRIMARY KEY key_schema key_schema := ( attribute_name HASH [, attribute_name RANGE]) billing_mode_and_throughput := (BILLING MODE ON DEMAND [throughput])|BILLING MODE provisioned) ...