texconfig-sys: 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/texconfig-sys - from package: texlive

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

On Debian possible default full paths are:

/usr/bin/texconfig-sys - from package: texlive-base

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

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