xsetroot: 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/xsetroot - from package: xorg-x11-server-utils

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

On Debian possible default full paths are:

/usr/bin/xsetroot - from package: x11-xserver-utils

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

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