jfs_tune: 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 CentOS possible default full paths are:

/sbin/jfs_tune - from package: jfsutils

You may install the required package with command yum install {package}

On Debian possible default full paths are:

/sbin/jfs_tune - from package: jfsutils

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

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