slonik: 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/slonik - from package: slony1-2-bin

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