skdump: 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/skdump - from package: libatasmart

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

On Debian possible default full paths are:

/usr/sbin/skdump - from package: libatasmart-bin

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

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