sadf: 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/bin/sadf - from package: sysstat

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

On Debian possible default full paths are:

/usr/bin/sadf - from package: sysstat

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

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