问Bash if条件中出现"unary operator expected“错误EN原文 条件语句和循环可以统称为流程控制，是一门语...
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 c...
Example 3: If statement in bash on less than a number In addition to-eqfor equality you can also try-lt -le -gt -getest conditions for less than, less than or equal, greater than or greater then or equal respectively. Below is a similar example with less then operator-lt: ...
Within the first Bash example of this article, we will be using the “if-not” operator to check which one of the two strings is less than the other. For this, we have added the Bash support within the file and added two new string variables v1 and v2. The value of v1 is a li...
并且执行会出错:unary operator expected,因为 = 是二元操作符,它需要左右各一个操作数。 如果变量值包含空格,它首先在执行之前进行单词拆分,因此 [命令看到的样子可能是这样的: [multiplewordshere="bar"]; 正确的做法应该是: #POSIX["$foo"=bar]
-ge 大于等于,如:if [ "a"−ge"b" ] -lt 小于,如:if [ "a"−lt"b" ] -le 小于等于,如:if [ "a"−le"b" ] < 小于(需要双括号),如:(("a"<"b")) <= 小于等于(需要双括号),如:(("a"<="b")) > 大于(需要双括号),如:(("a">"b")) ...
if [[ $foo =~ $re ]] 36. [ -n $foo ] or [ -z $foo ] 这个例子中, 没有用引号引起来,当foo 包含空格或者 $foo 为空时都会出问题: $ foo="some word" && [ -n $foo ] && echo yes -bash: [: some: binary operator expected ...
问在bash脚本中使用IF条件比较整数EN基本语法（比较常见的两种形式）： 只要特定条件为真，”while” ...
/usr/bin/env bash# File: simpleif.shecho"Start program"if[[$1-eq 4 ]]thenecho"You entered$1"fiecho"End program" 我们来看看运行结果,首先不带参数: $ bash simpleif.sh StartprogramEndprogram 带一个比4大的参数: $ bash simpleif.sh77StartprogramEndprogram...
bash: [: =: unary operator expected Which means the[was expecting a parameter found in thetestmanpage. 这意味着[期待在测试手册页中找到参数。 And, if I happen to have a filebarin my directory, the shell will replace*arwith all files that match that pattern (in this casebar), so the...