jabref: 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/jabref - from package: jabref

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

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