slirp: 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/slirp - from package: slirp

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

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