making a copy of a wordpress blog and setting it up on another domain

What I should have done:

Probably I should have used wp-cli to deactivate all plugins before the migration. And apparently, the whole thing could have been done far easily with wp-cli - https://rocketgeek.com/basics/using-wp-cli-to-migrate-copy-your-site/
https://guides.wp-bullet.com/migrate-wordpress-site-new-server-wp-cli/

Steps taken:

0. Ran all commands inside screen.

1. https://wordpress.stackexchange.com/questions/75135/how-to-export-import-wordpress-mysql-database-properly-via-command-line
says a normal mysqldump should suffice.

2. Mysqldump complained about permissions -
Error: 'Access denied; you need (at least one of) the PROCESS privilege(s) for this operation' when trying to dump tablespacesldump: Error: 'Access denied; you need (at least one of) the PROCESS privilege(s) for this operation' when trying to dump tablespaces

So, https://dba.stackexchange.com/questions/271981/access-denied-you-need-at-least-one-of-the-process-privileges-for-this-ope

SHOW GRANTS for someuser@localhost;.

To add the global privilege use the SQL command
GRANT PROCESS ON *.* TO someuser@localhost;

That solved the issue. In our case, I was running the SQL commands from the SQL console of dbeaver.

3. Created a new db as root, granted permissions for the relevant user as per https://www.digitalocean.com/community/tutorials/how-to-create-a-new-user-and-grant-permissions-in-mysql

4. mysql -u theuser -p thenewdb < wpdevelbackup.sql to populate the new db.

5. Copied over the directory with cp -a to retain permissions as well as do a recursive copy - https://unix.stackexchange.com/questions/44967/difference-between-cp-r-and-cp-a
sudo cp -a olddirectory newdirectory

6. After that, need to update the wp_options table in the new database. option_value like '%public_html%' showed all the required changes to be made after siteurl -
siteurl
home
astra_sites_recent_import_log_file
recently_edited
astra_sites_recent_import_log_file
fs_active_plugins
duplicator_package_active
uagb_downloaded_font_files
_transient_dirsize_cache

(Had to copy paste to text editor and find and replace for the multiple instances of the old path in some of these fields.

the _transient field was very big. Since anyway it would be recreated, deleted its value instead of changing the path to the new path for that value.)

7. Have to edit wp-config file also, since the site was redirecting back to the old url. https://www.sitepoint.com/how-to-migrate-a-wordpress-site-to-a-new-domain-and-hosting/
Had to add the
define('WP_HOME','https://oursite.com');
define('WP_SITEURL','https://oursite.com');
at the end of wp-config file also, since I had not de-activated the plugins before doing the migration. Or maybe just a caching problem with firefox which I used for testing. Site was working at this point, when tested with another browser. (I had done the editing of /etc/apache2/sites-available etc beforehand.)