mkpopular: 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/wims/bin/mkpopular - from package: wims

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

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