pgxn: 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/pgxn - from package: pgxnclient

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

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