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Questions tagged [debugging]

Debugging is a methodical process of finding and reducing the number of bugs, or defects, in a computer program

256 questions
186
votes
8 answers

I have a hardware detection problem, what logs do I need to look into?

I am trying to ask a question about getting my hardware to work but I don't know what information to add to my question to get help, what do I need to do? Related if you don't have access to a GUI: How do I get information from the logs on my…
Jorge Castro
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116
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9 answers

There's an issue with an Alpha/Beta Release of Ubuntu, what should I do?

I've been running Alpha releases of Ubuntu for some time now. I keep running into issues - how can I get these resolved? What should I do when I encounter these problems? And where can I find other Ubuntu+1 users to ask questions?
Marco Ceppi
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104
votes
8 answers

Nginx failing to reload - how to track down why?

Hi I've had my Nginx server running great on Ubuntu server 12.04 for a while. I've been gradually bolting on various bits, and got as far as optimising load times on my wordpress page. After making a few changes to my hosts file I decided to: sudo…
Huw
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73
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3 answers

after upgrade gdb won't attach to process

I just recently upgraded from 10.04 to 11.04 and gdb won't allow me to attach to processes anymore I get the error Attaching to process 10144 Could not attach to process. If your uid matches the uid of the target process, check the setting…
Andrew Redd
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71
votes
3 answers

Where do I find core dump files, and how do I view and analyze the backtrace (stack trace) in one?

When I run my C program on Ubuntu 20.04, I get this run-time error: Segmentation fault (core dumped) I really need to find and view the core file, but I can't find it anywhere. Where is it, and how do I view the backtrace in it?
Gabriel Staples
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68
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2 answers

How do I debug Upstart scripts?

For some reason I'm getting an error during apport upgrades, the cause of which is % sudo service apport start start: Job failed to start Under sysvinit, I could debug this kind of problem by running eg sudo sh -x /etc/init.d/whatever start but…
poolie
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38
votes
7 answers

How to debug bash script?

Is there any way to debug bash script without using echo and logging? I'm talking about using breakpoints and stuff like that.
UAdapter
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29
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2 answers

Why won't strace/gdb attach to a process even though I'm root?

I logged in as root but strace gives me this: root@kyznecov-System:/home/kyznecov# ps -e | grep 111 3807 pts/2 00:00:00 111 3810 pts/2 00:00:00 111 root@kyznecov-System:/home/kyznecov# strace -p 3810 attach: ptrace(PTRACE_ATTACH, ...):…
andreykyz
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26
votes
4 answers

Can one pick up a running application from terminal?

Sometime I need to run an application from terminal for debugging. If I am sure the bug will occur short after launching the application, I can run this application from the Terminal. However, bugs occur unexpectedly, and then only I need to monitor…
neydroydrec
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22
votes
2 answers

How can I find out what ibus-daemon and ibus-ui-gtk3 are doing?

Occasionally my desktop slows down a lot. The mouse pointer moves slowly or not at all, my fan starts whirring, and the end is generally nigh. If I'm very patient normality usually restores itself, but this happens daily. Recently when it happened I…
lofidevops
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16
votes
1 answer

Why do xrandr errors "BadMatch", "BadName", "Gamma Failed" happen?

I have not found a single solution to such errors, despite the rather large number of users out there who have them. So I want to try to find a solution myself. However, I have no idea why they occur... Is there anyone who knows why? You don't have…
TellMeWhy
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16
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1 answer

How to debug an unmet dependencies problem?

Note about possible duplicate: AFAIK, This is not a duplicate of How do I resolve unmet dependencies after adding a PPA? otherwise please prove it by solving the test problem I mention below using any answer from there. Background: I faced this…
user.dz
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15
votes
5 answers

How to install debug symbols for installed packages?

I try to watch how programs work by running them by the 'Qt Creator' debugger. For better orientation I'd like to see also the system (core) utilities fully in the call stack window as I am used from the MS Visual Studio 6.0, not only to see their…
Tomáš Pečený
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15
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1 answer

How can I debug my wireless problem?

How can I get started with debugging my wireless problem? How can I tell whether or not Linux has recognized my wireless hardware at all? What are the main programs/daemons associated with wireless connectivity? Where are the log files for those…
fouric
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14
votes
2 answers

How to load a module in initrd?

I want to explicitly load a module (say, netconsole) during the initrd stage, similarly to /etc/modules in the main system startup procedure. First, I checked that the initrd in my system already contains the wanted module (see Appendix). I have…
imz -- Ivan Zakharyaschev
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