distance_matrix_from_mapping.py: 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/qiime/bin/distance_matrix_from_mapping.py - from package: qiime

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

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