make_multi_seq: 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/make_multi_seq - from package: cd-hit

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

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