tcpbridge: 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/tcpbridge - from package: tcpreplay

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

On Debian possible default full paths are:

/usr/bin/tcpbridge - from package: tcpreplay

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

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