bg5conv: 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/bg5conv - from package: texlive-east-asian

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

On Debian possible default full paths are:

/usr/bin/bg5conv - from package: latex-cjk-chinese

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

Error in other languages:
bg5conv: bevel nie gevind nie
bg5conv: comandă negăsită
bg5conv: comando não encontrado
bg5conv: commande introuvable
bg5conv: command not found
bg5conv: käsku ei ole
bg5conv: không tìm thấy lệnh
bg5conv: komanda nerasta
bg5conv: Kommando nicht gefunden.
bg5conv: kommandot finns inte
bg5conv: komut yok
bg5conv: nie znaleziono polecenia
bg5conv: níor aimsíodh an t-ordú
bg5conv: no se encontró la orden
bg5conv: no s'ha trobat l'ordre
bg5conv: opdracht niet gevonden
bg5conv: parancs nem található
bg5conv: perintah tidak ditemukan
bg5conv: príkaz nenájdený
bg5conv: příkaz nenalezen
bg5conv: команда не найдена
bg5conv: командата не е открита
bg5conv: 命令找不到
bg5conv: コマンドが見つかりません