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"

以下是我的做法:

function help_text {
  printf "\n\
Usage: ./cpanel-to-cc.sh [arguments] ... \n\
Examples: \n\
\t ./cpanel-to-cc.sh --client-id 123123 --api-key abc123def456 --domain example.com \n\
\t ./cpanel-to-cc.sh --client-id 123123 --tmp-dir /home/user/cpanel-to-cc \n\
\t ./cpanel-to-cc.sh --resync --domain example.com \n\
\t ./cpanel-to-cc.sh --purge \n\
\n\
Arguments: \n\
Option \t\t\t Long option \t\t\t Function \n\
 -c <id> \t\t --client-id <id> \t\t Specify the SiteHost Client ID \n\
 -k <key> \t\t --api-key <key> \t\t Specify the SiteHost API key with access to Cloud, Job and Server modules \n\
 -d <domain> \t\t --domain <domain> \t\t The cPanel domain to migrate. If not specified we try migrate all \n\
 -t <directory> \t --tmp-dir <directory> \t\t Directory to store temporary files and logs. Default is: $TMP_DIR \n\
 -v \t\t\t --verbose \t\t\t Print debugging/verbose information \n\
 -y \t\t\t --assume-yes \t\t\t Automatic yes to prompts. Assume \"yes\" as answer to all prompts \n\
 -r \t\t\t --resync \t\t\t Use credentials stored and copy data into Container already created. \n\
 -p \t\t\t --purge \t\t\t Remove any metadata stored on the the server. This removes any files in: $TMP_DIR \n\
 -h \t\t\t --help \t\t\t Display this help and exit \n\
 \n"
}

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}"}

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。

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