filefrag: 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/filefrag - from package: e2fsprogs

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

On Debian possible default full paths are:

/usr/sbin/filefrag - from package: e2fsprogs
/usr/lib/debug/usr/sbin/filefrag - from package: e2fsprogs-dbg

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

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