octave-3.4.3: command not found

Have You tried accessing the binary with the full path?

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/octave-3.4.3 - from package: octave

You may install the required package with command yum install {package}
Error in other languages:
octave-3.4.3: bevel nie gevind nie
octave-3.4.3: comandă negăsită
octave-3.4.3: comando não encontrado
octave-3.4.3: commande introuvable
octave-3.4.3: command not found
octave-3.4.3: käsku ei ole
octave-3.4.3: không tìm thấy lệnh
octave-3.4.3: komanda nerasta
octave-3.4.3: Kommando nicht gefunden.
octave-3.4.3: kommandot finns inte
octave-3.4.3: komut yok
octave-3.4.3: nie znaleziono polecenia
octave-3.4.3: níor aimsíodh an t-ordú
octave-3.4.3: no se encontró la orden
octave-3.4.3: no s'ha trobat l'ordre
octave-3.4.3: opdracht niet gevonden
octave-3.4.3: parancs nem található
octave-3.4.3: perintah tidak ditemukan
octave-3.4.3: príkaz nenájdený
octave-3.4.3: příkaz nenalezen
octave-3.4.3: команда не найдена
octave-3.4.3: командата не е открита
octave-3.4.3: 命令找不到
octave-3.4.3: コマンドが見つかりません