find_member: 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 CentOS possible default full paths are:

/usr/lib/mailman/bin/find_member - from package: mailman

You may install the required package with command yum install {package}

On Debian possible default full paths are:

/usr/lib/mailman/bin/find_member - from package: mailman
/usr/sbin/find_member - from package: mailman

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

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