diameterc: 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/lib64/erlang/lib/diameter-0.10/bin/diameterc - from package: erlang-diameter

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

On Debian possible default full paths are:

/usr/bin/diameterc - from package: erlang-diameter
/usr/lib/erlang/lib/diameter-1.7.1/bin/diameterc - from package: erlang-diameter

You may install the required package with command apt-get install {package}

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