dh_installman: 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/bin/dh_installman - from package: debhelper

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