txt2mb: 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/txt2mb - from package: fcitx-tools

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

Error in other languages:
txt2mb: bevel nie gevind nie
txt2mb: comandă negăsită
txt2mb: comando não encontrado
txt2mb: commande introuvable
txt2mb: command not found
txt2mb: käsku ei ole
txt2mb: không tìm thấy lệnh
txt2mb: komanda nerasta
txt2mb: Kommando nicht gefunden.
txt2mb: kommandot finns inte
txt2mb: komut yok
txt2mb: nie znaleziono polecenia
txt2mb: níor aimsíodh an t-ordú
txt2mb: no se encontró la orden
txt2mb: no s'ha trobat l'ordre
txt2mb: opdracht niet gevonden
txt2mb: parancs nem található
txt2mb: perintah tidak ditemukan
txt2mb: príkaz nenájdený
txt2mb: příkaz nenalezen
txt2mb: команда не найдена
txt2mb: командата не е открита
txt2mb: 命令找不到
txt2mb: コマンドが見つかりません