exo-preferred-applications: 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/exo-preferred-applications - from package: exo

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

On Debian possible default full paths are:

/usr/bin/exo-preferred-applications - from package: exo-utils

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

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