mwrank: 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/mwrank - from package: eclib-tools

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

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