prettyseq: 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/prettyseq - from package: emboss

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

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