show_qfiles: 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/show_qfiles - 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/show_qfiles - from package: mailman

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

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