json2yaml: 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/json2yaml - from package: libghc-yaml-dev

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

Error in other languages:
json2yaml: bevel nie gevind nie
json2yaml: comandă negăsită
json2yaml: comando não encontrado
json2yaml: commande introuvable
json2yaml: command not found
json2yaml: käsku ei ole
json2yaml: không tìm thấy lệnh
json2yaml: komanda nerasta
json2yaml: Kommando nicht gefunden.
json2yaml: kommandot finns inte
json2yaml: komut yok
json2yaml: nie znaleziono polecenia
json2yaml: níor aimsíodh an t-ordú
json2yaml: no se encontró la orden
json2yaml: no s'ha trobat l'ordre
json2yaml: opdracht niet gevonden
json2yaml: parancs nem található
json2yaml: perintah tidak ditemukan
json2yaml: príkaz nenájdený
json2yaml: příkaz nenalezen
json2yaml: команда не найдена
json2yaml: командата не е открита
json2yaml: 命令找不到
json2yaml: コマンドが見つかりません