mysql_install_db: command not found

Maybe Your $PATH variable doesn't contain the default paths? echo $PATH should give something like:

[root@server ~]# echo $PATH
/usr/local/sbin:/usr/local/bin:/sbin:/bin:/usr/sbin:/usr/bin:/root/bin

If it's empty, You may set the PATH variable with this command

export PATH="/usr/local/sbin:/usr/local/bin:/sbin:/bin:/usr/sbin:/usr/bin:/root/bin"

On CentOS possible default full paths are:

/usr/bin/mysql_install_db - from package: mysql55w-server
/usr/bin/mysql_install_db - from package: mysql-server

You may install the required package with command yum install {package}

On Debian possible default full paths are:

/usr/bin/mysql_install_db - from package: mariadb-server-10.0
/usr/bin/mysql_install_db - from package: mysql-server-core-5.5

You may install the required package with command apt-get install {package}

Error in other languages:
mysql_install_db: bevel nie gevind nie
mysql_install_db: comandă negăsită
mysql_install_db: comando não encontrado
mysql_install_db: commande introuvable
mysql_install_db: command not found
mysql_install_db: käsku ei ole
mysql_install_db: không tìm thấy lệnh
mysql_install_db: komanda nerasta
mysql_install_db: Kommando nicht gefunden.
mysql_install_db: kommandot finns inte
mysql_install_db: komut yok
mysql_install_db: nie znaleziono polecenia
mysql_install_db: níor aimsíodh an t-ordú
mysql_install_db: no se encontró la orden
mysql_install_db: no s'ha trobat l'ordre
mysql_install_db: opdracht niet gevonden
mysql_install_db: parancs nem található
mysql_install_db: perintah tidak ditemukan
mysql_install_db: príkaz nenájdený
mysql_install_db: příkaz nenalezen
mysql_install_db: команда не найдена
mysql_install_db: командата не е открита
mysql_install_db: 命令找不到
mysql_install_db: コマンドが見つかりません