pstex2eps: 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/pstex2eps - from package: plplot

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

Error in other languages:
pstex2eps: bevel nie gevind nie
pstex2eps: comandă negăsită
pstex2eps: comando não encontrado
pstex2eps: commande introuvable
pstex2eps: command not found
pstex2eps: käsku ei ole
pstex2eps: không tìm thấy lệnh
pstex2eps: komanda nerasta
pstex2eps: Kommando nicht gefunden.
pstex2eps: kommandot finns inte
pstex2eps: komut yok
pstex2eps: nie znaleziono polecenia
pstex2eps: níor aimsíodh an t-ordú
pstex2eps: no se encontró la orden
pstex2eps: no s'ha trobat l'ordre
pstex2eps: opdracht niet gevonden
pstex2eps: parancs nem található
pstex2eps: perintah tidak ditemukan
pstex2eps: príkaz nenájdený
pstex2eps: příkaz nenalezen
pstex2eps: команда не найдена
pstex2eps: командата не е открита
pstex2eps: 命令找不到
pstex2eps: コマンドが見つかりません