gdalserver: 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/gdalserver - from package: gdal-bin

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

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