b2m: 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/b2m - from package: emacs-common

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

Error in other languages:
b2m: bevel nie gevind nie
b2m: comandă negăsită
b2m: comando não encontrado
b2m: commande introuvable
b2m: command not found
b2m: käsku ei ole
b2m: không tìm thấy lệnh
b2m: komanda nerasta
b2m: Kommando nicht gefunden.
b2m: kommandot finns inte
b2m: komut yok
b2m: nie znaleziono polecenia
b2m: níor aimsíodh an t-ordú
b2m: no se encontró la orden
b2m: no s'ha trobat l'ordre
b2m: opdracht niet gevonden
b2m: parancs nem található
b2m: perintah tidak ditemukan
b2m: príkaz nenájdený
b2m: příkaz nenalezen
b2m: команда не найдена
b2m: командата не е открита
b2m: 命令找不到
b2m: コマンドが見つかりません