aeson-pretty: 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/aeson-pretty - from package: aeson-pretty

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

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