applydeltarpm: 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/applydeltarpm - from package: deltarpm

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

On Debian possible default full paths are:

/usr/bin/applydeltarpm - from package: deltarpm

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

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