gnome-web-thumbnail: command not found

Have You tried accessing the binary with the full path?

Maybe Your $PATH variable doesn't contain the default paths? echo $PATH should give something like:

[root@server ~]# echo $PATH

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/gnome-web-thumbnail - from package: gnome-web-photo

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