mysqlindexcheck: 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/mysqlindexcheck - from package: mysql-utilities

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

On Debian possible default full paths are:

/usr/bin/mysqlindexcheck - from package: mysql-utilities

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

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