我如何在Bash中输出一个多重字符串,而不使用多个echo调用,像这样:

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

我正在寻找一种可移植的方法来做到这一点,只使用Bash内置程序。


当前回答

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。

其他回答

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。

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

然后

echo "$(</pathto/your_multiline_file)"

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"

我通常使用内置的read命令,我认为它更灵活和直观。 它将一行内容读入一个变量,并允许与特殊shell变量IFS绑定的分词。 更多细节请参考本博客或手册页。

read -r -d '' usage <<-EOF
    usage: up [--level <n>| -n <levels>][--help][--version] 

    Report bugs to: $report server
    up home page: $HOME
EOF
echo "$usage"