dbcheck.mysql: 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/sbin/dbcheck.mysql - from package: bacula-director-mysql

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

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