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/lib/heimdal/bin/rsh - from package: heimdal-appl-clients
/usr/kerberos/bin/rsh - from package: krb5-appl-clients
/usr/bin/rsh - from package: rsh

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

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