dh_installifupdown: 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/dh_installifupdown - from package: debhelper

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

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