bltk_install: 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/lib64/bltk/bin/bltk_install - from package: bltk

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

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