txt2tags: 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/txt2tags - from package: txt2tags

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

Error in other languages:
txt2tags: bevel nie gevind nie
txt2tags: comandă negăsită
txt2tags: comando não encontrado
txt2tags: commande introuvable
txt2tags: command not found
txt2tags: käsku ei ole
txt2tags: không tìm thấy lệnh
txt2tags: komanda nerasta
txt2tags: Kommando nicht gefunden.
txt2tags: kommandot finns inte
txt2tags: komut yok
txt2tags: nie znaleziono polecenia
txt2tags: níor aimsíodh an t-ordú
txt2tags: no se encontró la orden
txt2tags: no s'ha trobat l'ordre
txt2tags: opdracht niet gevonden
txt2tags: parancs nem található
txt2tags: perintah tidak ditemukan
txt2tags: príkaz nenájdený
txt2tags: příkaz nenalezen
txt2tags: команда не найдена
txt2tags: командата не е открита
txt2tags: 命令找不到
txt2tags: コマンドが見つかりません