opendkim-stats: 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/opendkim-stats - from package: opendkim-tools

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

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