serverspec-runner: 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/serverspec-runner - from package: serverspec-runner

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

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