xgfmerge: 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/xgfmerge - from package: xgridfit

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

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