sgfilter: 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/sgfilter - from package: sagator-core

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

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