txtconv: 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 CentOS possible default full paths are:

/usr/bin/txtconv - from package: teckit

You may install the required package with command yum install {package}

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