lshw-gtk: 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/lshw-gtk - from package: lshw-gtk

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

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