Can you see whats happening under the gui?

Question

When I start application with gui from linux terminal, i am able to see whats happening iunder the gui in that terminal. And if it crashes, most of the time there is problem why did it crashed. So my question is, is there possibility to view that kind of log when app is already running, and was started not from terminal, but using desktop environment, or something like dmenu. What about windows? Can you start app and see whats happening, and why does it crash?

Answer 1

Linux: No, AFAIK apps not started from a terminal will not necessarily have their STDOUT and STDERR directed anywhere useful. Not all apps write debugging/logging to STDOUT or STDERR. You should read the documentation or man pages for each application to see what logging options are available for each app. Many applications log to the syslog service. the syslog configuration determines how/where those log records are recorded. It isn't unusual for applications to have their own log files though.

You might want to read the man page for strace.

Windows: I'd look in the Event Viewer

Answer 2

Yes you can, but the location of the .log file containing the information in question depends on the application.

Most log files are in /var/log (you need to be su to access the directory). Some applications allow you to re-define the location of the log file, which in this case is typically to be found in /etc/applicationname.

If you cannot find anything relevant, you can search for the application name inside every file and subdirectory in the /var/log file as follows:

  cd /var/log
  grep -nrI openvpn

This will search for every mention of the word openvpn inside every file in all subdirectories of /var/log. The output of this query may be extensive, and require further filtering.