tcpreplay: 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/tcpreplay - from package: tcpreplay

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

On Debian possible default full paths are:

/usr/bin/tcpreplay - from package: tcpreplay

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

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