xemacs21-mule-canna-wnn: 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 Debian possible default full paths are:

/usr/bin/xemacs21-mule-canna-wnn - from package: xemacs21-mule-canna-wnn

You may install the required package with command apt-get install {package}
Error in other languages:
xemacs21-mule-canna-wnn: bevel nie gevind nie
xemacs21-mule-canna-wnn: comandă negăsită
xemacs21-mule-canna-wnn: comando não encontrado
xemacs21-mule-canna-wnn: commande introuvable
xemacs21-mule-canna-wnn: command not found
xemacs21-mule-canna-wnn: käsku ei ole
xemacs21-mule-canna-wnn: không tìm thấy lệnh
xemacs21-mule-canna-wnn: komanda nerasta
xemacs21-mule-canna-wnn: Kommando nicht gefunden.
xemacs21-mule-canna-wnn: kommandot finns inte
xemacs21-mule-canna-wnn: komut yok
xemacs21-mule-canna-wnn: nie znaleziono polecenia
xemacs21-mule-canna-wnn: níor aimsíodh an t-ordú
xemacs21-mule-canna-wnn: no se encontró la orden
xemacs21-mule-canna-wnn: no s'ha trobat l'ordre
xemacs21-mule-canna-wnn: opdracht niet gevonden
xemacs21-mule-canna-wnn: parancs nem található
xemacs21-mule-canna-wnn: perintah tidak ditemukan
xemacs21-mule-canna-wnn: príkaz nenájdený
xemacs21-mule-canna-wnn: příkaz nenalezen
xemacs21-mule-canna-wnn: команда не найдена
xemacs21-mule-canna-wnn: командата не е открита
xemacs21-mule-canna-wnn: 命令找不到
xemacs21-mule-canna-wnn: コマンドが見つかりません