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。

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"

使用-e选项，则可以在字符串中打印带\n的新行字符。

例如:

echo -e "This will be the first line \nand this will be on the second line"

还有一件事，使用printf和预定义的变量(这里:msg)作为模板。

msg="First line %s
Second line %s
Third line %s
"

one='additional message for the first line'
two='2'
tri='this is the last one'

printf "$msg" "$one" "$two" "$tri"

这个^^^将按指定的顺序打印整条消息，并插入额外的vars而不是%s。

或者你可以这样做:

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

Report bugs to: 
up home page: "

这样做:

dedent() {
    local -n reference="$1"
    reference="$(echo "$reference" | sed 's/^[[:space:]]*//')"
}

text="this is line one
      this is line two
      this is line three\n"

# `text` is passed by reference and gets dedented
dedent text

printf "$text"

不先调用dedent的输出:

this is line one
      this is line two
      this is line three

.．.和WITH首先调用dedent(如上所示):

this is line one
this is line two
this is line three

完整的解释，请看我已经写过的地方:

相当于python在bash中的textwrap dedent 带额外空格的多行字符串(保留缩进)

当然，感谢@Andreas Louv在这里向我展示了该函数的sed部分。