qfaxreader: command not found

Have You tried accessing the binary with the full path?

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/qfaxreader - from package: qfaxreader

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