xzdec: 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/xzdec - from package: xz

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

On Debian possible default full paths are:

/usr/bin/xzdec - from package: xzdec

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

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