fvwm-convert-2.4: 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/fvwm-convert-2.4 - from package: fvwm

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

On Debian possible default full paths are:

/usr/bin/fvwm-convert-2.4 - from package: fvwm

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

Error in other languages:
fvwm-convert-2.4: bevel nie gevind nie
fvwm-convert-2.4: comandă negăsită
fvwm-convert-2.4: comando não encontrado
fvwm-convert-2.4: commande introuvable
fvwm-convert-2.4: command not found
fvwm-convert-2.4: käsku ei ole
fvwm-convert-2.4: không tìm thấy lệnh
fvwm-convert-2.4: komanda nerasta
fvwm-convert-2.4: Kommando nicht gefunden.
fvwm-convert-2.4: kommandot finns inte
fvwm-convert-2.4: komut yok
fvwm-convert-2.4: nie znaleziono polecenia
fvwm-convert-2.4: níor aimsíodh an t-ordú
fvwm-convert-2.4: no se encontró la orden
fvwm-convert-2.4: no s'ha trobat l'ordre
fvwm-convert-2.4: opdracht niet gevonden
fvwm-convert-2.4: parancs nem található
fvwm-convert-2.4: perintah tidak ditemukan
fvwm-convert-2.4: príkaz nenájdený
fvwm-convert-2.4: příkaz nenalezen
fvwm-convert-2.4: команда не найдена
fvwm-convert-2.4: командата не е открита
fvwm-convert-2.4: 命令找不到
fvwm-convert-2.4: コマンドが見つかりません