mh_installsite: 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
/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_installsite - from package: maven-repo-helper

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