txt2mzml: 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/txt2mzml - from package: libpwiz-tools

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

Error in other languages:
txt2mzml: bevel nie gevind nie
txt2mzml: comandă negăsită
txt2mzml: comando não encontrado
txt2mzml: commande introuvable
txt2mzml: command not found
txt2mzml: käsku ei ole
txt2mzml: không tìm thấy lệnh
txt2mzml: komanda nerasta
txt2mzml: Kommando nicht gefunden.
txt2mzml: kommandot finns inte
txt2mzml: komut yok
txt2mzml: nie znaleziono polecenia
txt2mzml: níor aimsíodh an t-ordú
txt2mzml: no se encontró la orden
txt2mzml: no s'ha trobat l'ordre
txt2mzml: opdracht niet gevonden
txt2mzml: parancs nem található
txt2mzml: perintah tidak ditemukan
txt2mzml: príkaz nenájdený
txt2mzml: příkaz nenalezen
txt2mzml: команда не найдена
txt2mzml: командата не е открита
txt2mzml: 命令找不到
txt2mzml: コマンドが見つかりません