genreflex: 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/genreflex - from package: root-reflex

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

On Debian possible default full paths are:

/usr/bin/genreflex - from package: libroot-core-dev

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

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