members: 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/members - from package: members

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

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