matchbox-session: 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 Debian possible default full paths are:

/usr/bin/matchbox-session - from package: matchbox-common

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

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