猛砸判斷得到意想不到的結果

Question

這是我的shell腳本的代碼：

#! /bin/bash 

if ["$SHELL" = "/bin/bash"];then 
     echo "this is bash" 
elif ["$SHELL" = "aa"];then 
     echo "this is aa" 
else 
     echo "this is not /bin/bash, but $SHELL" 
fi 

爲什麼我執行test_bash_03腳本文件獲取else結果？它不應該是：this is bash

aircraftdeMacBook-Pro:bash_demo ldl$ ./test_bash_03 
./test_bash_03: line 3: [/bin/bash: No such file or directory 
./test_bash_03: line 5: [/bin/bash: No such file or directory 
this is not /bin/bash, but /bin/bash 

我附和$SHELL我也得到了/bin/bash

aircraftdeMacBook-Pro:bash_demo ldl$ echo $SHELL 
/bin/bash 

Answer 1

你缺少一個空間[後]之前。

bash嘗試執行名爲[/bin/bash而不是[（即test）的命令，然後未找到該命令並且退出代碼爲1（false）。所以你最終在else的情況下。