rrdinfo: 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/rrdinfo - from package: rrdtool

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

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