jffs2dump: 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/sbin/jffs2dump - from package: mtd-utils

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

Error in other languages:
jffs2dump: bevel nie gevind nie
jffs2dump: comandă negăsită
jffs2dump: comando não encontrado
jffs2dump: commande introuvable
jffs2dump: command not found
jffs2dump: käsku ei ole
jffs2dump: không tìm thấy lệnh
jffs2dump: komanda nerasta
jffs2dump: Kommando nicht gefunden.
jffs2dump: kommandot finns inte
jffs2dump: komut yok
jffs2dump: nie znaleziono polecenia
jffs2dump: níor aimsíodh an t-ordú
jffs2dump: no se encontró la orden
jffs2dump: no s'ha trobat l'ordre
jffs2dump: opdracht niet gevonden
jffs2dump: parancs nem található
jffs2dump: perintah tidak ditemukan
jffs2dump: príkaz nenájdený
jffs2dump: příkaz nenalezen
jffs2dump: команда не найдена
jffs2dump: командата не е открита
jffs2dump: 命令找不到
jffs2dump: コマンドが見つかりません