yaml2json: 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/yaml2json - from package: libghc-yaml-dev

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

Error in other languages:
yaml2json: bevel nie gevind nie
yaml2json: comandă negăsită
yaml2json: comando não encontrado
yaml2json: commande introuvable
yaml2json: command not found
yaml2json: käsku ei ole
yaml2json: không tìm thấy lệnh
yaml2json: komanda nerasta
yaml2json: Kommando nicht gefunden.
yaml2json: kommandot finns inte
yaml2json: komut yok
yaml2json: nie znaleziono polecenia
yaml2json: níor aimsíodh an t-ordú
yaml2json: no se encontró la orden
yaml2json: no s'ha trobat l'ordre
yaml2json: opdracht niet gevonden
yaml2json: parancs nem található
yaml2json: perintah tidak ditemukan
yaml2json: príkaz nenájdený
yaml2json: příkaz nenalezen
yaml2json: команда не найдена
yaml2json: командата не е открита
yaml2json: 命令找不到
yaml2json: コマンドが見つかりません