vfychain: 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/vfychain - from package: libnss3-tools

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

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