hugin_hdrmerge: 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/hugin_hdrmerge - from package: hugin-tools

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

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