JFractionLab.jar: 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/share/jfractionlab/bin/JFractionLab.jar - from package: jfractionlab

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

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