Backup MySQL users
mysql -BNe "select concat('\'',user,'\'@\'',host,'\'') from mysql.user where user != 'root'" | \while read uh; do mysql -BNe "show grants for $uh" | sed 's/$/;/; s/\\\\/\\/g'; done > grants.sql
You can backup mysql database using
mysqldump -u root -p mysql > mysql.sqland restore mysql database by executing
mysql -uroot -p mysql < mysql.sqlDont forget to
FLUSH PRIVILEGES
after restoring dump.
Hope it helps...
So far my experience with MySQL i didn't see anything to backup user and their privileges through a command line.
But i can backup those critical data by backing up mysql
mysqldump -u root -p mysql > mysql.sql