heimdal-rsh: 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-rsh - from package: heimdal-appl-clients

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

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