leaf: command not found

Have You tried accessing the binary with the full path?

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/leaf - from package: cone

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