filter-fontlint: 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/filter-fontlint - from package: fontpackages-tools

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

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