dmtxread: 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/dmtxread - from package: libdmtx-utils

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

On Debian possible default full paths are:

/usr/bin/dmtxread - from package: dmtx-utils

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

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