wmsetbg: 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/wmsetbg - from package: WindowMaker

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

On Debian possible default full paths are:

/usr/bin/wmsetbg - from package: wmaker

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

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