bash shell脚本提示输入数据库密码

Question

I added a shell script I use all the time in cronjobs for a new account. When I ran it (under sudo -u) I got prompted for the database password. When supplied with pass the command completed without issue.

The random password the host had assigned started with a $ and I wondered if that was issue so I modified to have pass in variable. The current script is below.

When run it still prompts for db password before successfully completing. What is wrong there?

#!/bin/sh

DBPASS="$randomlettersarehere"

/usr/bin/mysqldump --opt -h mysql.mysite.com -u myuser -p$DBPASS mydbname > "/home/mysite/backups/"`/bin/date +\%Y\%m\%d`.mysiteBackup.sql

Answer 1

Use single quotes to prevent $letters from being interpreted as a variable name.

DBPASS='$randomlettersarehere'

When you use double quotes the shell performs variable interpolation. With the dollar sign at the start, that means $DBPASS ends up being an empty string.

Answer 2

以防它像我一样帮助别人：字符串以$开头，因此bash不会将sring插值为未定义变量

DBPASS='$randomlettersarehere'