krsh: 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/kerberos/bin/krsh - from package: krb5-appl-clients

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

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