tex-skipped-unit: 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/lib64/piglit/bin/tex-skipped-unit - from package: piglit

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

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