sim4: 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/sim4 - from package: sim4

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

Error in other languages:
sim4: bevel nie gevind nie
sim4: comandă negăsită
sim4: comando não encontrado
sim4: commande introuvable
sim4: command not found
sim4: käsku ei ole
sim4: không tìm thấy lệnh
sim4: komanda nerasta
sim4: Kommando nicht gefunden.
sim4: kommandot finns inte
sim4: komut yok
sim4: nie znaleziono polecenia
sim4: níor aimsíodh an t-ordú
sim4: no se encontró la orden
sim4: no s'ha trobat l'ordre
sim4: opdracht niet gevonden
sim4: parancs nem található
sim4: perintah tidak ditemukan
sim4: príkaz nenájdený
sim4: příkaz nenalezen
sim4: команда не найдена
sim4: командата не е открита
sim4: 命令找不到
sim4: コマンドが見つかりません