cback-amazons3-sync: command not found

Have You tried accessing the binary with the full path?

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/cback-amazons3-sync - from package: cedar-backup2

You may install the required package with command apt-get install {package}
Error in other languages:
cback-amazons3-sync: bevel nie gevind nie
cback-amazons3-sync: comandă negăsită
cback-amazons3-sync: comando não encontrado
cback-amazons3-sync: commande introuvable
cback-amazons3-sync: command not found
cback-amazons3-sync: käsku ei ole
cback-amazons3-sync: không tìm thấy lệnh
cback-amazons3-sync: komanda nerasta
cback-amazons3-sync: Kommando nicht gefunden.
cback-amazons3-sync: kommandot finns inte
cback-amazons3-sync: komut yok
cback-amazons3-sync: nie znaleziono polecenia
cback-amazons3-sync: níor aimsíodh an t-ordú
cback-amazons3-sync: no se encontró la orden
cback-amazons3-sync: no s'ha trobat l'ordre
cback-amazons3-sync: opdracht niet gevonden
cback-amazons3-sync: parancs nem található
cback-amazons3-sync: perintah tidak ditemukan
cback-amazons3-sync: príkaz nenájdený
cback-amazons3-sync: příkaz nenalezen
cback-amazons3-sync: команда не найдена
cback-amazons3-sync: командата не е открита
cback-amazons3-sync: 命令找不到
cback-amazons3-sync: コマンドが見つかりません