calgebra: 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 Debian possible default full paths are:

/usr/bin/calgebra - from package: calgebra

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

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