ttfcoverage: 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/ttfcoverage - from package: fontpackages-tools

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

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