carbon-c-relay: 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/carbon-c-relay - from package: carbon-c-relay

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