Reset mysql root password on unix without needing old password.

mysql-reset-root-pw.sh

#!/bin/bash

MYSQL_ROOT_PASSWORD=$1

if [ -z "$MYSQL_ROOT_PASSWORD" ]; then
    echo 'Missing required $1 (password).'
    exit 1
fi

# check if mysql is running now.
mysqlrunning=$(service mysqld status | grep 'running')

if [ ! -z "$mysqlrunning" ]; then
    echo "stopping mysql"
    service mysqld stop
fi

echo "starting with skip grants"
mysqld_safe --skip-grant-tables >/dev/null 2>&1 &

sleep 10

# Get pid to kill later.
PID_FILE=$(echo 'show variables like "pid_file"' | mysql --defaults-file=/dev/null -N -u root | awk '{print $2}')
PID=$(cat $PID_FILE)

echo "resetting pw"
mysql --defaults-file=/dev/null -u root mysql << EOF
UPDATE user set authentication_string=password('$MYSQL_ROOT_PASSWORD') WHERE user='root';  
FLUSH PRIVILEGES;
EOF

sleep 10

echo "stopping mysql"
kill $PID

# restart mysql if was running before.
if [ ! -z "$mysqlrunning" ]; then
    echo "starting mysql as normal"
    sleep 5
    service mysqld start
fi