yaws: 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/yaws - from package: yaws

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

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