mh_clean: 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/mh_clean - from package: maven-repo-helper

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

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