fedmsg-dg-replay: 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/fedmsg-dg-replay - from package: fedmsg

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

On Debian possible default full paths are:

/usr/bin/fedmsg-dg-replay - from package: fedmsg

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

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