xsetbg: 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/xsetbg - from package: xloadimage

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

On Debian possible default full paths are:

/usr/bin/xsetbg - from package: xloadimage

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

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