find_SH_peaks: 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/find_SH_peaks - from package: mrtrix

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

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