haproxyctl: command not found

Have You tried accessing the binary with the full path?

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/haproxyctl - from package: haproxyctl

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