debconf-mergetemplate: 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/debconf-mergetemplate - from package: debconf-utils

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

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