tachyon-ogl: 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/tachyon-ogl - from package: tachyon-gl

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

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