vpassert: 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/vpassert - from package: perl-Verilog-Perl

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

On Debian possible default full paths are:

/usr/bin/vpassert - from package: libverilog-perl

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

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