extresso: 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/extresso - from package: icoutils

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

On Debian possible default full paths are:

/usr/bin/extresso - from package: icoutils

You may install the required package with command apt-get install {package}

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