tab2txt1: 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/lib/unicon/bin/tab2txt1 - from package: unicon-imc2

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

Error in other languages:
tab2txt1: bevel nie gevind nie
tab2txt1: comandă negăsită
tab2txt1: comando não encontrado
tab2txt1: commande introuvable
tab2txt1: command not found
tab2txt1: käsku ei ole
tab2txt1: không tìm thấy lệnh
tab2txt1: komanda nerasta
tab2txt1: Kommando nicht gefunden.
tab2txt1: kommandot finns inte
tab2txt1: komut yok
tab2txt1: nie znaleziono polecenia
tab2txt1: níor aimsíodh an t-ordú
tab2txt1: no se encontró la orden
tab2txt1: no s'ha trobat l'ordre
tab2txt1: opdracht niet gevonden
tab2txt1: parancs nem található
tab2txt1: perintah tidak ditemukan
tab2txt1: príkaz nenájdený
tab2txt1: příkaz nenalezen
tab2txt1: команда не найдена
tab2txt1: командата не е открита
tab2txt1: 命令找不到
tab2txt1: コマンドが見つかりません