flwm: 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/flwm - from package: flwm

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

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