libdecodeqr-simpletest: 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/libdecodeqr-simpletest - from package: libdecodeqr-examples

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

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