unixserver: 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/bin/unixserver - from package: ucspi-unix

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

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