b4b5-archfix: 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/lib/mailman/bin/b4b5-archfix - from package: mailman

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

On Debian possible default full paths are:

/usr/lib/mailman/bin/b4b5-archfix - from package: mailman

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

Error in other languages:
b4b5-archfix: bevel nie gevind nie
b4b5-archfix: comandă negăsită
b4b5-archfix: comando não encontrado
b4b5-archfix: commande introuvable
b4b5-archfix: command not found
b4b5-archfix: käsku ei ole
b4b5-archfix: không tìm thấy lệnh
b4b5-archfix: komanda nerasta
b4b5-archfix: Kommando nicht gefunden.
b4b5-archfix: kommandot finns inte
b4b5-archfix: komut yok
b4b5-archfix: nie znaleziono polecenia
b4b5-archfix: níor aimsíodh an t-ordú
b4b5-archfix: no se encontró la orden
b4b5-archfix: no s'ha trobat l'ordre
b4b5-archfix: opdracht niet gevonden
b4b5-archfix: parancs nem található
b4b5-archfix: perintah tidak ditemukan
b4b5-archfix: príkaz nenájdený
b4b5-archfix: příkaz nenalezen
b4b5-archfix: команда не найдена
b4b5-archfix: командата не е открита
b4b5-archfix: 命令找不到
b4b5-archfix: コマンドが見つかりません