ospfclient: 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/ospfclient - from package: quagga

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

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