dbcheck.postgresql: 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.postgresql - from package: bacula-director-postgresql

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

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