libvirtd: 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/sbin/libvirtd - from package: libvirt

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

On Debian possible default full paths are:

/usr/sbin/libvirtd - from package: libvirt-daemon
/usr/lib/debug/usr/sbin/libvirtd - from package: libvirt0-dbg

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

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