citserver: 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/lib/debug/usr/sbin/citserver - from package: citadel-dbg
/usr/sbin/citserver - from package: citadel-server

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

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