是否有用于bash脚本的所有if开关的列表？有时我看到有人使用它，我想知道他们使用的开关实际上是做什么的。
示例是此中的-z。我知道如何使用它，但我不知道它的来源。
if [ -z "$BASH_VERSION" ]; then
echo -e "Error: this script requires the BASH shell!"
exit 1
fi
任何参考，指南，帖子，答案将不胜感激。
看看bash手册页(man bash)。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 ...
它也在帮助中解释：
$ help [ [: [ arg... ]
This is a synonym for the "test" builtin,but the last
argument must be a literal `]',to match the opening `['.
