Running a Script to change a wp-config file DB Name - linux

Question

I teach students how to fix wordpress sites and I would like to write a script that looks at what information they have in their wp-config.php and add a single letter or number to the database name.
For example the line is such
define('DB_NAME', 'cpanelUser_NameofDB');
I would like to add a number or a line to the end of NameofDB
I can use this to isolate the cpanelUser_NameofDB
grep -i 'DB_NAME' wp-config.php | cut -d"'" -f4
but I'm not sure how to add information, nor if this is the correct script I should run to get there. I would also like it to not matter what the name of the database is since it will be ran on multiple sites. I'm sure I could use regex but I'm not too versed in that and would not know where to start. Help please!

Answer 1

You can use WP CLI on the server:
Go to the website root:
cd /var/www/mysite.com/htdocs
...and list all the wp-config values:
wp config list
...or set the value you need to change:
sudo wp config set DB_NAME put_my_custom_db_name_here --allow-root
See more WP CONFIG features here:
https://developer.wordpress.org/cli/commands/config/

Answer 2

You can use sed for this purpose to fix this line:
#!/bin/bash
id=34
sed -i "s/^.*DB_NAME.*$/define('DB_NAME', 'cpanelUser_NameofDB${id}');/" wp-config.php
flag -i means that we do change in file directly.
Alternatively you can make template file and generate new file while sed works on stdin and stdout
#!/bin/bash
id=34
cat wp-config.php-template| sed "s/^.*DB_NAME.*$/define('DB_NAME', 'cpanelUser_NameofDB${id}');/" > wp-config.php.$id