fst2vcd: 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/fst2vcd - from package: gtkwave

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

On Debian possible default full paths are:

/usr/bin/fst2vcd - from package: gtkwave

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

Error in other languages:
fst2vcd: bevel nie gevind nie
fst2vcd: comandă negăsită
fst2vcd: comando não encontrado
fst2vcd: commande introuvable
fst2vcd: command not found
fst2vcd: käsku ei ole
fst2vcd: không tìm thấy lệnh
fst2vcd: komanda nerasta
fst2vcd: Kommando nicht gefunden.
fst2vcd: kommandot finns inte
fst2vcd: komut yok
fst2vcd: nie znaleziono polecenia
fst2vcd: níor aimsíodh an t-ordú
fst2vcd: no se encontró la orden
fst2vcd: no s'ha trobat l'ordre
fst2vcd: opdracht niet gevonden
fst2vcd: parancs nem található
fst2vcd: perintah tidak ditemukan
fst2vcd: príkaz nenájdený
fst2vcd: příkaz nenalezen
fst2vcd: команда не найдена
fst2vcd: командата не е открита
fst2vcd: 命令找不到
fst2vcd: コマンドが見つかりません