heimdal-login: 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/heimdal-login - from package: heimdal-appl-clients

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

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