if grep -q SomeString "$File"; then
  Some Actions # SomeString was found
fi

这里不需要 [[ ]].直接运行命令就行了.当您不需要找到时显示的字符串时，添加 -q 选项.

You don't need [[ ]] here. Just run the command directly. Add -q option when you don't need the string displayed when it was found.

grep 命令在退出代码中返回 0 或 1，具体取决于搜索的结果.0 如果找到了一些东西；1 否则.

The grep command returns 0 or 1 in the exit code depending on the result of search. 0 if something was found; 1 otherwise.

$ echo hello | grep hi ; echo $?
1
$ echo hello | grep he ; echo $?
hello
0
$ echo hello | grep -q he ; echo $?
0

你可以指定命令作为if的条件.如果命令在其退出代码中返回 0，则表示条件为真；否则为假.

You can specify commands as an condition of if. If the command returns 0 in its exitcode that means that the condition is true; otherwise false.

$ if /bin/true; then echo that is true; fi
that is true
$ if /bin/false; then echo that is true; fi
$

如您所见，您可以直接在此处运行程序.没有额外的 [] 或 [[]].

As you can see you run here the programs directly. No additional [] or [[]].