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

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

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