rrdcollect: 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/lib/debug/usr/sbin/rrdcollect - from package: rrdcollect-dbg
/usr/sbin/rrdcollect - from package: rrdcollect

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

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