pyFAI-saxs: 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/pyFAI-saxs - from package: pyfai

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

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