btwisted: 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/btwisted - from package: emboss

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

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