innobackupex: 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 Debian possible default full paths are:

/usr/bin/innobackupex - from package: percona-xtrabackup

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

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