ip6tables-save-1.4.7: 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 CentOS possible default full paths are:

/sbin/ip6tables-save-1.4.7 - from package: iptables-ipv6

You may install the required package with command yum install {package}

Error in other languages:
ip6tables-save-1.4.7: bevel nie gevind nie
ip6tables-save-1.4.7: comandă negăsită
ip6tables-save-1.4.7: comando não encontrado
ip6tables-save-1.4.7: commande introuvable
ip6tables-save-1.4.7: command not found
ip6tables-save-1.4.7: käsku ei ole
ip6tables-save-1.4.7: không tìm thấy lệnh
ip6tables-save-1.4.7: komanda nerasta
ip6tables-save-1.4.7: Kommando nicht gefunden.
ip6tables-save-1.4.7: kommandot finns inte
ip6tables-save-1.4.7: komut yok
ip6tables-save-1.4.7: nie znaleziono polecenia
ip6tables-save-1.4.7: níor aimsíodh an t-ordú
ip6tables-save-1.4.7: no se encontró la orden
ip6tables-save-1.4.7: no s'ha trobat l'ordre
ip6tables-save-1.4.7: opdracht niet gevonden
ip6tables-save-1.4.7: parancs nem található
ip6tables-save-1.4.7: perintah tidak ditemukan
ip6tables-save-1.4.7: príkaz nenájdený
ip6tables-save-1.4.7: příkaz nenalezen
ip6tables-save-1.4.7: команда не найдена
ip6tables-save-1.4.7: командата не е открита
ip6tables-save-1.4.7: 命令找不到
ip6tables-save-1.4.7: コマンドが見つかりません