Conditional commands in ssh & shell & mysql

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 [email protected] 
    "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?

$? contains the int return code of the last run command. 0 is success. — diolemo
– diolemo, Commented Feb 3, 2013 at 22:22

F. Hauri - Give Up GitHub · Accepted Answer · 2013-02-03 22:36:19Z

2

You could chain all in one block:

mysqldump -u root files path |
    gzip -9 |
     ssh -i ~/metadata.pem [email protected] "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.

answered Feb 3, 2013 at 22:36

F. Hauri - Give Up GitHub

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Comments

Zulu · Accepted Answer · 2013-02-03 22:24:39Z

1

You can use $? for get return code of last command, if it's not 0, it failed.

Or you can use && for example : cmd1 && cmd2.

Or you can use set -e to stop script if occur an error.

answered Feb 3, 2013 at 22:24

Zulu

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