ldconfig: 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:

/sbin/ldconfig - from package: glibc

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

On Debian possible default full paths are:

/sbin/ldconfig - from package: libc-bin
/usr/src/glibc/debian/local/sbin/ldconfig - from package: glibc-source

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

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