UNIX测试何时在测试命令中使用eq vs = vs ==？

我什么时候应该使用-eqvs =vs==

例如

[[ $num -eq 0 ]]

[[ $num = 'zzz' ]]

我观察到了使用-eq（和-ne等）数字和=字符串的模式。是否有这个原因，什么时候应该使用==

因为那是这些操作数的定义。从POSIX测试文档中，“操作数”部分：

s1 = s2

如果字符串s1和s2相同，则为true；否则为true。否则为假。

...

n1 -eq n2

如果整数n1和n2代数相等，则为true；否则为true。否则为假。

==不是由POSIX定义的，它是的扩展bash，从继承而来ksh。==当您想要便携性时，您不应该使用。从bash文档-Bash条件表达式：

字符串1 ==字符串2

字符串1 =字符串2

如果字符串相等，则为真。为测试POSIX一致性，应将'='与test命令一起使用。

以下序列可以更详尽地帮助您：

gnu:~$ [ sam -eq sam ]  
bash: [: sam: integer expression expected  
gnu:~$ echo "Exit status of \"[ sam -eq sam ]\" is $?."  
Exit status of "[ sam -eq sam ]" is 2.  

gnu:~$ [ 5 -eq 5 ]  
gnu:~$ echo "Exit status of \"[ 5 -eq 5 ]\" is $?."  
Exit status of "[ 5 -eq 5 ]" is 0.  

gnu:~$ [ 5 = 5 ]  
gnu:~$ echo "Exit status of \"[ 5 = 5 ]\" is $?."  
Exit status of "[ 5 = 5 ]" is 0.  

gnu:~$ [ sam = sam ]  
gnu:~$ echo "Exit status of \"[ sam = sam ]\" is $?."  
Exit status of "[ sam = sam ]" is 0.  

gnu:~$ [ 5 == 5 ]  
gnu:~$ echo "Exit status of \"[ 5 == 5 ]\" is $?."  
Exit status of "[ 5 == 5 ]" is 0.  

gnu:~$ [ sam == sam ]  
gnu:~$ echo "Exit status of \"[ sam == sam ]\" is $?."  
Exit status of "[ sam == sam ]" is 0.  

gnu:~$ (( 5 == 5 ))  
gnu:~$ echo "Exit status of \"(( 5 == 5 ))\" is $?."  
Exit status of "(( 5 == 5 ))" is 0.  

gnu:~$ (( sam == sam ))  
gnu:~$ echo "Exit status of \"(( sam == sam ))\" is $?."  
Exit status of "(( sam == sam ))" is 0.  

gnu:~$ ( sam = sam )  
The program 'sam' is currently not installed. You can install it by typing:  
sudo apt-get install simon  
gnu:~$ echo "Exit status of \"( sam = sam )\" is $?."  
Exit status of "( sam = sam )" is 127.  

gnu:~$ ( 5 = 5 )  
5: command not found  
gnu:~$ echo "Exit status of \"( 5 = 5 )\" is $?."  
Exit status of "( 5 = 5 )" is 127.  

gnu:~$ ( sam == sam )  
The program 'sam' is currently not installed. You can install it by typing:  
sudo apt-get install simon  
gnu:~$ echo "Exit status of \"( sam == sam )\" is $?."  
Exit status of "( sam == sam )" is 127.  

gnu:~$ ( 5 == 5 )  
5: command not found  
gnu:~$ echo "Exit status of \"( 5 == 5 )\" is $?."  
Exit status of "( 5 == 5 )" is 127.  

来自man test：

-eq 等

中继到算术测试。参数必须全部为数字（可能为负），或特殊表达式“ -l STRING”，其计算结果为STRING的长度。

STRING1 = STRING2

 True if the strings are equal.

STRING1 == STRING2

 True if the strings are equal (synonym for =).

所以=和==是同义词

Symbol =用于字符串比较，而-eq用于整数比较。都可与test和一起使用[...]。如果您正在使用bashthen语法[[...]]，则还可以==用于字符串比较。此外，在庆典=，并==与[[...]]对工作patterns太（作为例子[[ $x == y* ]]。