dia-gnome: 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/dia-gnome - from package: dia-gnome

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

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