Declare variable in Bash?

Question

I'm connected to my DB from the bash. I do a select count of an array and I want to stock the return in a variable. How can I do that?

I did:

var=`"select count(*) from shop_tab where catalog <> ''" | mysql -h abcdcef.com --port=3306 --user=root --password=hbbfe shop`

The request return a number but it doesn't stock into the variable.

Thanks!

EDIT: It works with this command line:

myvar = $(echo "select count(*) from shop_tab where catalog <> '';" | mysql -h abcdcef.com --port=3306 --user=root --password=hbbfe shop)

What is the content of `var` after you run this? (`echo $var`) — carlpett, Jul 20 '11 at 09:04
Does this help? [http://stackoverflow.com/questions/1636977/bash-script-select-from-database-into-variable][1] [1]: http://stackoverflow.com/questions/1636977/bash-script-select-from-database-into-variable — Raanan W, Jul 20 '11 at 09:13
You have to do it all on one line, since the variable isn't being exported: `var=XmycommandX; echo $var` (replace `X` by the backtick, I don't know how to escape the backtick in the comment box). Also use `-e` rather than piping. — Kerrek SB, Jul 20 '11 at 09:13

Arnaud F. · Answer 1 · 2011-07-20T09:44:19.030

An easier way is :

var=$(mysql -h abcdcef.com --port=3306 --user=root --password=hbbfe --batch --skip-column-names -Dshop -e "select count(*) from shop_tab where catalog <> ''")

Moreover, I'll preconize the use of function in order to easily add options to the MySQL command without having to modifying all your script.

function MysqlQuery() {
    mysql -h abcdcef.com --port=3306 --user=root --password=hbbfe --batch --skip-column-names -D "$1" -e "$2";
}

va=$(MysqlQuery Shop "SELECT COUNT(*) FROM shop_tab WHERE catalog <> ''")
vaABC=$(MysqlQuery Shop "SELECT COUNT(*) FROM shop_tab WHERE catalog <> 'abc'")
vadef=$(MysqlQuery Shop "SELECT COUNT(*) FROM shop_tab WHERE catalog <> 'def'")
# ...

I find this more readable too...

score 1 · Answer 2 · answered Jul 20 '11 at 09:10

1

I think you are forgetting an echo in the pipe? Like this:

var=`echo "select count(*) from shop_tab where catalog <> ''" | mysql -h abcdcef.com --port=3306 --user=root --password=hbbfe shop`

answered Jul 20 '11 at 09:10

carlpett

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1

Well spotted! One more reason not to do any piping at all and instead use `mysql -e`. – Kerrek SB Jul 20 '11 at 09:14

Declare variable in Bash?

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