rrdcreate: 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 Debian possible default full paths are:

/usr/bin/rrdcreate - from package: rrdtool

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

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