dialog-config: command not found

Have You tried accessing the binary with the full path?

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

[root@server ~]# echo $PATH

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/dialog-config - from package: dialog-devel

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