base64tool: 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/base64tool - from package: mkvtoolnix

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

Error in other languages:
base64tool: bevel nie gevind nie
base64tool: comandă negăsită
base64tool: comando não encontrado
base64tool: commande introuvable
base64tool: command not found
base64tool: käsku ei ole
base64tool: không tìm thấy lệnh
base64tool: komanda nerasta
base64tool: Kommando nicht gefunden.
base64tool: kommandot finns inte
base64tool: komut yok
base64tool: nie znaleziono polecenia
base64tool: níor aimsíodh an t-ordú
base64tool: no se encontró la orden
base64tool: no s'ha trobat l'ordre
base64tool: opdracht niet gevonden
base64tool: parancs nem található
base64tool: perintah tidak ditemukan
base64tool: príkaz nenájdený
base64tool: příkaz nenalezen
base64tool: команда не найдена
base64tool: командата не е открита
base64tool: 命令找不到
base64tool: コマンドが見つかりません