openbox: 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/openbox - from package: openbox

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

On Debian possible default full paths are:

/usr/bin/openbox - from package: openbox

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

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