seqboot: 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
/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/lib/phylip/bin/seqboot - from package: phylip

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