um_attach: 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/bin/um_attach - from package: umview

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