tm_eukleides: command not found

Have You tried accessing the binary with the full path?

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/libexec/TeXmacs/bin/tm_eukleides - from package: TeXmacs

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