xfsmdiag: command not found

Have You tried accessing the binary with the full path?

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/sbin/xfsmdiag - from package: ax25-xtools

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