tunegfs2: 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:

/usr/sbin/tunegfs2 - from package: gfs2-utils

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

On Debian possible default full paths are:

/usr/sbin/tunegfs2 - from package: gfs2-utils

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

Error in other languages:
tunegfs2: bevel nie gevind nie
tunegfs2: comandă negăsită
tunegfs2: comando não encontrado
tunegfs2: commande introuvable
tunegfs2: command not found
tunegfs2: käsku ei ole
tunegfs2: không tìm thấy lệnh
tunegfs2: komanda nerasta
tunegfs2: Kommando nicht gefunden.
tunegfs2: kommandot finns inte
tunegfs2: komut yok
tunegfs2: nie znaleziono polecenia
tunegfs2: níor aimsíodh an t-ordú
tunegfs2: no se encontró la orden
tunegfs2: no s'ha trobat l'ordre
tunegfs2: opdracht niet gevonden
tunegfs2: parancs nem található
tunegfs2: perintah tidak ditemukan
tunegfs2: príkaz nenájdený
tunegfs2: příkaz nenalezen
tunegfs2: команда не найдена
tunegfs2: командата не е открита
tunegfs2: 命令找不到
tunegfs2: コマンドが見つかりません