vvp: 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 CentOS possible default full paths are:

/usr/bin/vvp - from package: iverilog

You may install the required package with command yum install {package}

On Debian possible default full paths are:

/usr/bin/vvp - from package: iverilog

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

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