carbon-hosts: 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/carbon-hosts - from package: carbonate

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

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