Since I recommended printf in a comment, I should probably give some examples of its usage (although for printing a usage message, I'd be more likely to use Dennis' or Chris' answers). printf is a bit more complex to use than echo. Its first argument is a format string, in which escapes (like \n) are always interpreted; it can also contain format directives starting with %, which control where and how any additional arguments are included in it. Here are two different approaches to using it for a usage message:

首先，你可以在格式字符串中包含整个消息:

printf "usage: up [--level <n>| -n <levels>][--help][--version]\n\nReport bugs to: \nup home page: \n"

注意，与echo不同，必须显式地包含最后的换行符。此外，如果消息碰巧包含%字符，则必须将它们写成%%。如果你想包含bugreport和主页地址，它们可以很自然地添加:

printf "usage: up [--level <n>| -n <levels>][--help][--version]\n\nReport bugs to: %s\nup home page: %s\n" "$bugreport" "$homepage"

其次，你可以使用format字符串让它在单独的行中打印每个额外的参数:

printf "%s\n" "usage: up [--level <n>| -n <levels>][--help][--version]" "" "Report bugs to: " "up home page: "

使用这个选项，添加bugreport和主页地址是相当明显的:

printf "%s\n" "usage: up [--level <n>| -n <levels>][--help][--version]" "" "Report bugs to: $bugreport" "up home page: $homepage"

受到本页上富有洞察力的回答的启发，我创造了一个混合的方法，我认为这是最简单和更灵活的方法。你怎么看?

首先，我在一个变量中定义了它的用法，这允许我在不同的上下文中重用它。格式非常简单，几乎是所见即所得，不需要添加任何控制字符。对我来说，这似乎是合理的可移植性(我在MacOS和Ubuntu上运行它)

__usage="
Usage: $(basename $0) [OPTIONS]

Options:
  -l, --level <n>              Something something something level
  -n, --nnnnn <levels>         Something something something n
  -h, --help                   Something something something help
  -v, --version                Something something something version
"

那么我就可以简单地把它用作

echo "$__usage"

或者更好的是，当解析参数时，我可以在一行中回显它:

levelN=${2:?"--level: n is required!""${__usage}"}

或者你可以这样做:

echo "usage: up [--level <n>| -n <levels>][--help][--version]

Report bugs to: 
up home page: "

    You can write your
    text
        freely,
                   in a separate: 
                             ----file.

然后

echo "$(</pathto/your_multiline_file)"

同样，对于缩进的源代码，您可以使用<<-(带末尾破折号)来忽略前面的制表符(但不能忽略前面的空格)。

比如这个:

if [ some test ]; then
    cat <<- xx
        line1
        line2
xx
fi

输出不带前导空格的缩进文本:

line1
line2

在这里，文档通常用于此目的。

cat << EOF
usage: up [--level <n>| -n <levels>][--help][--version]

Report bugs to: 
up home page:
EOF

所有boure派生的shell(包括所有版本的Bash)都支持它们。