es2tri: 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 Debian possible default full paths are:

/usr/bin/es2tri - from package: mesa-utils-extra

You may install the required package with command apt-get install {package}
Error in other languages:
es2tri: bevel nie gevind nie
es2tri: comandă negăsită
es2tri: comando não encontrado
es2tri: commande introuvable
es2tri: command not found
es2tri: käsku ei ole
es2tri: không tìm thấy lệnh
es2tri: komanda nerasta
es2tri: Kommando nicht gefunden.
es2tri: kommandot finns inte
es2tri: komut yok
es2tri: nie znaleziono polecenia
es2tri: níor aimsíodh an t-ordú
es2tri: no se encontró la orden
es2tri: no s'ha trobat l'ordre
es2tri: opdracht niet gevonden
es2tri: parancs nem található
es2tri: perintah tidak ditemukan
es2tri: príkaz nenájdený
es2tri: příkaz nenalezen
es2tri: команда не найдена
es2tri: командата не е открита
es2tri: 命令找不到
es2tri: コマンドが見つかりません