rexima: 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/rexima - from package: rexima

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