darkplaces-dedicated: 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/bin/darkplaces-dedicated - from package: darkplaces-server

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

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