nbibtex: 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 Debian possible default full paths are:

/usr/bin/nbibtex - from package: nbibtex

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

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