Linux bash command with quotes - inside quotes - inside quotes

Question

I have this command that runs fine - mysql -p$DB_PW -u ops --host="$DB_ENDPOINT" -e "delete from users.webservers where ipaddress='$PRIVATE_IP';"

I want to run it with a different user so I have to put the command inside single quotes but it then will now work -

sudo -H -u ernie bash -c 'mysql -p$DB_PW -u ops --host="$DB_ENDPOINT" -e "delete from users.webservers where ipaddress='$PRIVATE_IP';"'

Any help is appreciated!

Answer 1

You don't need to run bash ; sudo will run mysql just fine.

sudo -H -u ernie \
    mysql -p"$DB_PW" \
          -u ops \
          --host="$DB_ENDPOINT" \
          -e "delete from users.webservers where ipaddress='$PRIVATE_IP';"

Note that there is a risk of a SQL injection attack; be sure you know what the value of PRIVATE_IP is before executing this command.

Answer 2

Your second layer of quotes ( " ) will have no problems being nested inside ' quotes. Your most nested layer must be escaped. To escape single quotes, use

'\''

instead of '

Technically, this is not escaping single quotes, this is ending the previous quoted section, writing a literal ' , and then starting a new quoted section. This is how bash is designed to handle single quotes that must be nested inside other single quotes.