seedtop: 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/seedtop - from package: blast2
/usr/share/ncbi-blast+/bin/seedtop - from package: ncbi-blast+-legacy

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

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