popularity-contest: 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/sbin/popularity-contest - from package: popularity-contest

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

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