filter-unicover: 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-unicover - from package: fontpackages-tools

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

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