popcon-process.sh: command not found

Have You tried accessing the binary with the full path?

Maybe Your $PATH variable doesn't contain the default paths? echo $PATH should give something like:

[root@server ~]# echo $PATH

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/share/doc/popularity-contest/examples/bin/popcon-process.sh - from package: popularity-contest

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