md5sum.textutils: 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/bin/md5sum.textutils - from package: coreutils

You may install the required package with command apt-get install {package}
Error in other languages:
md5sum.textutils: bevel nie gevind nie
md5sum.textutils: comandă negăsită
md5sum.textutils: comando não encontrado
md5sum.textutils: commande introuvable
md5sum.textutils: command not found
md5sum.textutils: käsku ei ole
md5sum.textutils: không tìm thấy lệnh
md5sum.textutils: komanda nerasta
md5sum.textutils: Kommando nicht gefunden.
md5sum.textutils: kommandot finns inte
md5sum.textutils: komut yok
md5sum.textutils: nie znaleziono polecenia
md5sum.textutils: níor aimsíodh an t-ordú
md5sum.textutils: no se encontró la orden
md5sum.textutils: no s'ha trobat l'ordre
md5sum.textutils: opdracht niet gevonden
md5sum.textutils: parancs nem található
md5sum.textutils: perintah tidak ditemukan
md5sum.textutils: príkaz nenájdený
md5sum.textutils: příkaz nenalezen
md5sum.textutils: команда не найдена
md5sum.textutils: командата не е открита
md5sum.textutils: 命令找不到
md5sum.textutils: コマンドが見つかりません