sim_client: 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/sim_client - from package: krb5-devel

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

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