yapps: 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/yapps - from package: yapps2

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

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