如何在Bash中的Heredoc之后使用控件运算符

Question

我正在编写一个bash脚本来自动创建MySQL数据库。 bash脚本类似于以下内容（请忽略那些变量$ db_name，$ db_pwd ...）：

#!/bin/bash
sudo mysql -u root << EOF
    CREATE DATABASE $db_name;
    CREATE USER $db_user IDENTIFIED BY $db_pwd;
    GRANT ALL PRIVILEGES ON $db_name.* TO $db_user;
    quit
EOF
printf "Done"

我希望数据库创建成功完成，然后运行print命令。 但是我不能将&&放在EOF之后，例如：

#!/bin/bash
sudo mysql -u root << EOF
    CREATE DATABASE $db_name;
    CREATE USER $db_user IDENTIFIED BY $db_pwd;
    GRANT ALL PRIVILEGES ON $db_name.* TO $db_user;
    quit
EOF &&
printf "Done"

它将显示如下错误：

invalid command name "EOF"
    while executing
"EOF &&"

我该怎么做？

Answer 1

一个简单的解决方法是，如果mysql失败，则退出。

sudo mysql -u root << EOF || exit
    CREATE DATABASE $db_name;
    CREATE USER $db_user IDENTIFIED BY $db_pwd;
    GRANT ALL PRIVILEGES ON $db_name.* TO $db_user;
EOF
echo "Done"

或者，您可以添加set -e导致任何失败的命令立即退出脚本。

#!/bin/bash
set -e

sudo mysql -u root << EOF
    CREATE DATABASE $db_name;
    CREATE USER $db_user IDENTIFIED BY $db_pwd;
    GRANT ALL PRIVILEGES ON $db_name.* TO $db_user;
EOF
echo "Done"

Answer 2

解析很奇怪，但是可以习惯了。 |之后的换行符（和评论） && || 被忽略。 因此，您只需在命令的末尾写上，但是在<< EOF

#!/bin/bash
sudo mysql -u root << EOF &&
    CREATE DATABASE $db_name;
    CREATE USER $db_user IDENTIFIED BY $db_pwd;
    GRANT ALL PRIVILEGES ON $db_name.* TO $db_user;
    quit
EOF
printf "Done"

例：

grep -q bla << EOF &&
bla bla
EOF
# this comment is ignored

# lines with spaces, tabs and newlines and comments only are ignored
# until the first line with something is encountered
# the following will execute only if grep returns zero status
# it can be misleading

# Because you can write a LOT here, but bash stil just sees `grep && printf`
printf "grep matched successfully"

在tutorialspoint的示例。

Answer 3

将sudo放入圆括号中：

#!/bin/bash
(sudo mysql -u root << EOF
   ...
EOF
) && [next command]