lookbib: 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/lookbib - from package: groff

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

On Debian possible default full paths are:

/usr/bin/lookbib - from package: groff

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

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