Bash Script not running MySQL Command

Question

I have a MySQL command in a bash script I'm running. I'm running other Linux command line commands before this one (in fact one is even a mysql command) but when it gets to this one, it doesn't work:

DEST_HOST="localhost"
DEST_DBNAME="db_name"
DEST_DBUSER="root"
DEST_DBPASS=""

# FILE NAME
MIGRATION_FILE="migration_database"

# Export/Import Commands
DO_DATABASE_UPDATE="mysql --host=$SOURCE_HOST --user=$DEST_DBUSER --password $DEST_DBNAME < $MIGRATION_FILE.sql"

echo 'Running local updates...'
$DO_DATABASE_UPDATE

echo "$DO_DATABASE_UPDATE"

# Done!
echo "Complete!"

I have the migration_database.sql file in the folder that I'm running it from. As you can see, I'm printing out the UPDATE command at the end of everything. What happens is that I run this and it just prints on the mysql menu like I ran mysql -I to get the help menu.

If I copy and paste the command that is printed out and run it, it works great. I'm not sure why bash doesn't execute this from within the script.

Any ideas?

Answer 1

... --password $DEST_DBNAME

You don't pass your database password. You just use the --password option with no argument, which means, "prompt me to type the password." If you run this script in a non-interactive shell, you'll never see the prompt.

You could set the password as an argument:

... --password='$DEST_DBPASS' $DEST_DBNAME

Or actually what I would recommend is that you do not put your username & password on the command-line at all, because that's not a good security habit.

Instead, put the username and password in a config file and tell your command to use that config file.

DO_DATABASE_UPDATE="mysql --defaults-extra-file=$HOME/migration.cnf $DEST_DBNAME < $MIGRATION_FILE.sql"

In your migration.cnf:

[client]
host = localhost
user = root
password = xxxxxxxx

If you're using MySQL 5.6 or later, you should also learn about mysql_config_editor so you can store those account credentials in an encrypted file.

---

Re your comment:

Is there some issue using a less than sign in a command in a bash variable?

Yes there is an issue. It seems the order of evaluation in shell processes redirection before variable expansion. My apologies for not noticing that before.

If I were writing your script I would write it either this way:

DO_DATABASE_UPDATE="mysql ...opts..."
echo 'Running local updates...'
$DO_DATABASE_UPDATE $DEST_DBNAME < $MIGRATION_FILE.sql

Or else this way:

DO_DATABASE_UPDATE="mysql ...opts... $DEST_DBNAME -e 'source $MIGRATION_FILE.sql'"
echo 'Running local updates...'
$DO_DATABASE_UPDATE

Answer 2

MySQL Command From a Bash Shell in One Line

Use the following command for quickly execution of MySQL query from a Linux Bash Shell : # mysql -u [user] -p[pass] -e "[mysql commands]"

Example :

# mysql -u root -pSeCrEt -e "show databases"

Run a MySQL Query From a Bash script using EOF Use the following syntax in your Bash scripts for running MySQL commands :

mysql -u [user] -p[pass] << EOF
[mysql commands]
EOF

Example :

#!/bin/bash
mysql -u root -pSeCrEt << EOF
use mysql;
show tables;
EOF

Execute a MySQL Command Remotely Use -h option to specify a MySQL server's IP address:

# mysql -h [ip] -u [user] -p[pass] -e "[mysql commands]"

Example :

# mysql -h 192.168.1.10 -u root -pSeCrEt -e "show databases"

Specify a Database to Use

Use -D option to specify the name of MySQL database :
# mysql -D [db name] -u [user] -p[pass] -e "[mysql commands]"

Example :

# mysql -D clients -u root -pSeCrEt -e "show tables"