ydump: 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/ydump - from package: libyojson-ocaml-dev

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

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