genext2fs: 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/genext2fs - from package: genext2fs

You may install the required package with command apt-get install {package}
Error in other languages:
genext2fs: bevel nie gevind nie
genext2fs: comandă negăsită
genext2fs: comando não encontrado
genext2fs: commande introuvable
genext2fs: command not found
genext2fs: käsku ei ole
genext2fs: không tìm thấy lệnh
genext2fs: komanda nerasta
genext2fs: Kommando nicht gefunden.
genext2fs: kommandot finns inte
genext2fs: komut yok
genext2fs: nie znaleziono polecenia
genext2fs: níor aimsíodh an t-ordú
genext2fs: no se encontró la orden
genext2fs: no s'ha trobat l'ordre
genext2fs: opdracht niet gevonden
genext2fs: parancs nem található
genext2fs: perintah tidak ditemukan
genext2fs: príkaz nenájdený
genext2fs: příkaz nenalezen
genext2fs: команда не найдена
genext2fs: командата не е открита
genext2fs: 命令找不到
genext2fs: コマンドが見つかりません