glookbib: 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/glookbib - from package: groff

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

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