omindex: 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/omindex - from package: xapian-omega

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

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