mmseg: 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 Debian possible default full paths are:

/usr/bin/mmseg - from package: sunpinyin-utils

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

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