csdeconv: 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/lib/mrtrix/bin/csdeconv - from package: mrtrix

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

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