gvnccapture: 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/gvnccapture - from package: gvncviewer

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

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