traceroute6.iputils: 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/traceroute6.iputils - from package: iputils-tracepath

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

Error in other languages:
traceroute6.iputils: bevel nie gevind nie
traceroute6.iputils: comandă negăsită
traceroute6.iputils: comando não encontrado
traceroute6.iputils: commande introuvable
traceroute6.iputils: command not found
traceroute6.iputils: käsku ei ole
traceroute6.iputils: không tìm thấy lệnh
traceroute6.iputils: komanda nerasta
traceroute6.iputils: Kommando nicht gefunden.
traceroute6.iputils: kommandot finns inte
traceroute6.iputils: komut yok
traceroute6.iputils: nie znaleziono polecenia
traceroute6.iputils: níor aimsíodh an t-ordú
traceroute6.iputils: no se encontró la orden
traceroute6.iputils: no s'ha trobat l'ordre
traceroute6.iputils: opdracht niet gevonden
traceroute6.iputils: parancs nem található
traceroute6.iputils: perintah tidak ditemukan
traceroute6.iputils: príkaz nenájdený
traceroute6.iputils: příkaz nenalezen
traceroute6.iputils: команда не найдена
traceroute6.iputils: командата не е открита
traceroute6.iputils: 命令找不到
traceroute6.iputils: コマンドが見つかりません