db_hotbackup: 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/db_hotbackup - from package: db4-utils

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

On Debian possible default full paths are:

/usr/bin/db_hotbackup - from package: db-util

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

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