bash 如何在bash脚本中将变量传递给SSH命令
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How to pass variables to SSH command in bash script
提问by JP Lew
I am new to bash scripting, and am attempting write a script to sync my local Wordpress database with a remote one. Here it is:
我是 bash 脚本的新手，正在尝试编写一个脚本来将我的本地 Wordpress 数据库与远程数据库同步。这里是：
#!/bin/sh
RUSER=example-admin
RHOST=ftp.example.com
RDBUSER=wp_admin
RDB=wp_db
RDBHOST=localhost
RBAK=.backup/latest-remote-db.mssql
LUSER=root
LPASS=root
LHOST=localhost
LDB=wp_db
LBAK=.backup/latest-local-db.mssql
#dump the contents of my local database
mysqldump -u$LUSER -p$LPASS -h $LHOST $LDB > $LBAK
#upload my local database to remote
scp $LBAK $RUSER@$RHOST:~/.backup/
#login to remote host, backup remote database, delete the remote database then recreate it, restore it with the contents of my local database
ssh $RUSER@$RHOST 'mysqldump -uwp_admin -h localhost wp_db > ~/.backup/latest-remote-db.mssql; mysql -uwp_admin -h localhost -Bse "show databases; drop database wp_db; create database wp_db;"; mysql -uwp_admin -h localhost wp_db < ~/.backup/latest-local-db.mssql;'
The above works fine, yet I'm not satisfied with the final sshcommand because all the values are hard-coded. I would prefer to use something like this:
以上工作正常，但我对最终ssh命令不满意，因为所有值都是硬编码的。我更喜欢使用这样的东西：
ssh $RUSER@$RHOST 'mysqldump -u$RDBUSER -h $RDBHOST $RDB > ~/$RBAK; mysql -u$RDBUSER -h $RDBHOST -Bse "drop database $RDB; create database $RDB;"; mysql -u$RDBUSER -h $RDBHOST $RDB < ~/$LBAK;'
However this obviously does not work, because the all the variables are trapped inside quotes and therefore don't get substituted. Can anybody advise on a better way to achieve this? I considered executing a separate script on the remote end to handle all the mysqlcommands, yet that strikes me as more inefficient.
然而，这显然不起作用，因为所有变量都被困在引号内，因此不会被替换。有人可以建议更好的方法来实现这一目标吗？我考虑在远程端执行一个单独的脚本来处理所有mysql命令，但我觉得这效率更低。
采纳答案by dogbane
Use double-quotes for the outermost quotes so that variables are expanded. Use single quotes inside.
对最外面的引号使用双引号，以便扩展变量。在里面使用单引号。
Try this:
尝试这个：
ssh $RUSER@$RHOST "mysqldump -u$RDBUSER -h $RDBHOST $RDB > ~/$RBAK; mysql -u$RDBUSER -h $RDBHOST -Bse 'drop database $RDB; create database $RDB;'; mysql -u$RDBUSER -h $RDBHOST $RDB < ~/$LBAK;"
