crxvt-big5: 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/crxvt-big5 - from package: rxvt-ml

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

Error in other languages:
crxvt-big5: bevel nie gevind nie
crxvt-big5: comandă negăsită
crxvt-big5: comando não encontrado
crxvt-big5: commande introuvable
crxvt-big5: command not found
crxvt-big5: käsku ei ole
crxvt-big5: không tìm thấy lệnh
crxvt-big5: komanda nerasta
crxvt-big5: Kommando nicht gefunden.
crxvt-big5: kommandot finns inte
crxvt-big5: komut yok
crxvt-big5: nie znaleziono polecenia
crxvt-big5: níor aimsíodh an t-ordú
crxvt-big5: no se encontró la orden
crxvt-big5: no s'ha trobat l'ordre
crxvt-big5: opdracht niet gevonden
crxvt-big5: parancs nem található
crxvt-big5: perintah tidak ditemukan
crxvt-big5: príkaz nenájdený
crxvt-big5: příkaz nenalezen
crxvt-big5: команда не найдена
crxvt-big5: командата не е открита
crxvt-big5: 命令找不到
crxvt-big5: コマンドが見つかりません