tracker-needle: command not found

Have You tried accessing the binary with the full path?

Maybe Your $PATH variable doesn't contain the default paths? echo $PATH should give something like:

[root@server ~]# echo $PATH

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/tracker-needle - from package: tracker-gui

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