netkit-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 Debian possible default full paths are:

/usr/bin/netkit-rsh - from package: rsh-client

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

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