mapper: 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/mapper - from package: dnssec-tools

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

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