desktop-file-validate: 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/desktop-file-validate - from package: desktop-file-utils

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

On Debian possible default full paths are:

/usr/bin/desktop-file-validate - from package: desktop-file-utils

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

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