tm_gnuplot: 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_gnuplot - from package: TeXmacs

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

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