fedmsg-tail: command not found

Have You tried accessing the binary with the full path?

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-tail - from package: fedmsg

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

On Debian possible default full paths are:

/usr/bin/fedmsg-tail - from package: fedmsg

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