dh_php5: 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_php5 - from package: dh-php5

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

Error in other languages:
dh_php5: bevel nie gevind nie
dh_php5: comandă negăsită
dh_php5: comando não encontrado
dh_php5: commande introuvable
dh_php5: command not found
dh_php5: käsku ei ole
dh_php5: không tìm thấy lệnh
dh_php5: komanda nerasta
dh_php5: Kommando nicht gefunden.
dh_php5: kommandot finns inte
dh_php5: komut yok
dh_php5: nie znaleziono polecenia
dh_php5: níor aimsíodh an t-ordú
dh_php5: no se encontró la orden
dh_php5: no s'ha trobat l'ordre
dh_php5: opdracht niet gevonden
dh_php5: parancs nem található
dh_php5: perintah tidak ditemukan
dh_php5: príkaz nenájdený
dh_php5: příkaz nenalezen
dh_php5: команда не найдена
dh_php5: командата не е открита
dh_php5: 命令找不到
dh_php5: コマンドが見つかりません