lshw-gui: 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/lshw-gui - from package: lshw-gui
/usr/sbin/lshw-gui - from package: lshw-gui

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

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