crxvt-gb: 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-gb - from package: rxvt-ml

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

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