gdlib-config: 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/gdlib-config - from package: gd-devel

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

On Debian possible default full paths are:

/usr/bin/gdlib-config - from package: libgd-dev

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

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