guiqwt-tests: 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/guiqwt-tests - from package: python-guiqwt

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

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