swift-ring-builder: 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/swift-ring-builder - from package: swift

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