mylvmbackup: 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/mylvmbackup - from package: mylvmbackup

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

On Debian possible default full paths are:

/usr/bin/mylvmbackup - from package: mylvmbackup

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

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