slpd: 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/sbin/slpd - from package: openslp-server

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

On Debian possible default full paths are:

/usr/sbin/slpd - from package: slpd

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

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