ogr2ogr: 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/ogr2ogr - from package: gdal

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

On Debian possible default full paths are:

/usr/bin/ogr2ogr - from package: gdal-bin

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

Error in other languages:
ogr2ogr: bevel nie gevind nie
ogr2ogr: comandă negăsită
ogr2ogr: comando não encontrado
ogr2ogr: commande introuvable
ogr2ogr: command not found
ogr2ogr: käsku ei ole
ogr2ogr: không tìm thấy lệnh
ogr2ogr: komanda nerasta
ogr2ogr: Kommando nicht gefunden.
ogr2ogr: kommandot finns inte
ogr2ogr: komut yok
ogr2ogr: nie znaleziono polecenia
ogr2ogr: níor aimsíodh an t-ordú
ogr2ogr: no se encontró la orden
ogr2ogr: no s'ha trobat l'ordre
ogr2ogr: opdracht niet gevonden
ogr2ogr: parancs nem található
ogr2ogr: perintah tidak ditemukan
ogr2ogr: príkaz nenájdený
ogr2ogr: příkaz nenalezen
ogr2ogr: команда не найдена
ogr2ogr: командата не е открита
ogr2ogr: 命令找不到
ogr2ogr: コマンドが見つかりません