gdalmanage: 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/gdalmanage - from package: gdal

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

On Debian possible default full paths are:

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

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

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