geos-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/geos-config - from package: geos-devel

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

On Debian possible default full paths are:

/usr/bin/geos-config - from package: libgeos-dev

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

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