Question

I have the following commands in a shell script where I do a mysql dump, then I load that SQL file over ssh into a remote database, and then I update the timestamp.

1. mysqldump -u root files path | gzip -9 > $SQL_FILE
2. cat $SQL_FILE | ssh -i ~/metadata.pem ubuntu@1.2.3.4 
    "zcat | mysql -u 'root' -h 1.2.3.4 metadata"
3. TIMESTAMP=`date "+%Y-%m-%d-%T"`
4. mysql -u 'root' -h 1.2.3.4 metadata -e "UPDATE path_last_updated SET timestamp=DEFAULT"

Is there any way to improve the above commands. For example, what happens if line 2 fails (for example, due to a connectivity issue), but line 4 succeeds?

How would I make line 4 running conditional on the success of line 2?

Answer 1

You could chain all in one block:

mysqldump -u root files path |
    gzip -9 |
     ssh -i ~/metadata.pem ubuntu@1.2.3.4 "zcat |\
                   mysql -u 'root' -h 1.2.3.4 metadata"  &&
    mysql -u 'root' -h 1.2.3.4 metadata -e "
        UPDATE path_last_updated SET timestamp=DEFAULT"

So last mysql command won’t be executed if something fail before.