bash - 任何地方都有 'if' 开关列表吗？

Question

是否有用于 Bash 脚本的所有 if 开关的列表？有时我看到有人在使用它，我想知道他们使用的开关实际上有什么作用。

一个例子是这个中的-z。我知道如何使用它，但我不知道它来自哪里。

if [ -z "$BASH_VERSION" ]; then
    echo -e "Error: this script requires the BASH shell!"
    exit 1
fi

任何引用、指南、帖子、答案都将不胜感激。

Answer 1

查看 Bash 手册页 (man bash)。这些选项在 CONDITIONAL EXPRESSIONS 部分中指定:

CONDITIONAL EXPRESSIONS
       Conditional expressions are used by the [[  compound  command  and  the
       test  and [ builtin commands to test file attributes and perform string
       and arithmetic comparisons.  Expressions are formed from the  following
       unary  or  binary  primaries.   If any file argument to one of the pri-
       maries is of the form /dev/fd/n, then file descriptor n is checked.  If
       the  file  argument  to  one  of  the  primaries  is one of /dev/stdin,
       /dev/stdout, or /dev/stderr, file descriptor 0, 1, or 2,  respectively,
       is checked.

       Unless otherwise specified, primaries that operate on files follow sym-
       bolic links and operate on the target of the link, rather than the link
       itself.

       -a file
              True if file exists.
       ... more options ...

帮助中也有说明:

$ help [
[: [ arg... ]
    This is a synonym for the "test" builtin, but the last
    argument must be a literal `]', to match the opening `['.