is a process of finding and reducing the number of bugs, or defects, in a computer program, thus making it behave as expected

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39
votes
2answers
837 views

How did `git pull` eat my homework?

I feel like a kid in the principal's office explaining that the dog ate my homework the night before it was due, but I'm staring some crazy data loss bug in the face and I can't figure out how it ...
3
votes
1answer
82 views

How to save the result of printf to a variable in GDB?

(gdb)printf "Hello %d", 7 Hello 7 (gdb)set $MyVar = printf "Hello %d", 7 // ??? How to save the result of printf "Hello %d", 7 to $MyVar?
3
votes
1answer
103 views

How to make gdb not ask me “y or n”?

When I use GDB command add-symbol-file to load the symbol, GDB always asks me 'y or n', like this: gdb> add-symbol-file mydrv.ko 0xa0070000 add symbol table from file "mydrv.ko" at ...
5
votes
2answers
4k views

How to enable crash reports/core dumps/stack trace logging globally?

Crashing bugs can be the most annoying ones, leading to data loss, downtime and frustrated users. It would be good if applications crashed less. Because of the complexity of the machine context, ...
3
votes
1answer
50 views

Methods to find out which (configuration) files are read by executable when started

What are the clever ways to find out which (configuration) files are read by executable if started? For example snmpd or sshd. One option is probably to check the CONFIGURATION FILES or FILES section ...
2
votes
1answer
94 views

sysrq-trigger doesn't accept parameter 'g'

I'm trying to debug the kernel. But I couldn't trigger kgdb with echo g > /proc/sysrq-trigger, it just prints help message. I have enabled kernel debugging, kgdb over serial, frame pointer etc. ...
1
vote
2answers
4k views

How to detect a possible hardware error?

I'm running Debian Wheezy on a HP Pavilion dv7 laptop and it freezes every now and then, requiring a reboot. One time it didn't even load the operating system, but it wasn't I who was using it so I ...
2
votes
2answers
123 views

How can I remotely debug a broken initrd?

Background I have a system that runs Linux. It's a NAS, and does not have any monitor, keyboard, or serial port. It does have a network port. I'm not happy with the software running on it, and am ...
5
votes
2answers
340 views

How to determine what instructions a process is executing?

I know about strace and ltrace, but that only tells me what system calls and library calls a process is executing, respectively. I would like to know exactly what instructions a process is executing. ...
3
votes
0answers
41 views

Kernel bisect: when a patch is failing for a reason other than original bisect purpose, what do you do? [closed]

Let's say you're trying to find the cause of a bug between 3.11.0 and 3.12.0. The bug is really difficult to catch, because it may or may not manifest itself over several days of regular workload ...
9
votes
4answers
370 views

How can I tell if the currently executing bash script has been invoked with -x for debugging?

I have a script launch.sh that executes itself as another user so as to create files with the correct owner. I want to pass -x to this invocation if it was originally passed to the script if [ ...
4
votes
3answers
212 views

Adding comments using 'set -x'

Sometimes it is really handy to just add set -x to the top of your script to show all commands before they are executed. There is only one drawback creating scripts with a decent output: I don't ...
4
votes
1answer
847 views

How to dump USB traffic?

I got an USB gamepad and I would like to see and inspect the signals and commands that this peripherals is actually sending to my PC/kernel: how I can do that ? I was assuming that something like ...
2
votes
0answers
129 views

An obscure autotools error with Epson iscan project

I'm seeing the following error when attempting to build iscan using the master branch on Debian wheezy. This project provides support for Epson scanners, in cases when SANE doesn't. This project ...
1
vote
1answer
138 views

What's a good way to debug issues with X forwarding over ssh where just some applications won't run?

As far as I understand it, X forwarding is usually pretty simple. Once I can run some things like xeyes or gimp over ssh, complex applications like firefox/iceweasel should also be able to run. ...
0
votes
1answer
770 views

How to enable printk selectively?

I want to print some statements from kernel but not all. So can I use printk selectively? By selectively I mean I want to enable printk only at particular places and disable it everywhere else. ...
1
vote
1answer
156 views

How to extract running Apache configuration from core dump?

Apache is loading the configuration from files into its memory. If the config files are changing the Apache process won't activate it until a reload/restart happens. Now I have to debug the current ...
0
votes
1answer
568 views

Debug program in eclipse with a newly built compiler

I recently tried to build the new version of GCC (4.8.1) on Ubuntu 12.04. I managed to build everything correctly, it passed the tests and I installed the new compiler. I can build programs with the ...
1
vote
2answers
139 views

Why does Linux print a lot of debugging messages on boot/shutdown?

Why does Linux print a lot of debugging messages during the boot and shutdown processes? The boot/shutdown processes usually have no error. Why not hide the debugging messages, and show them only ...
0
votes
2answers
81 views

Emacs how do I interpret this Lisp debugger report

I am trying to make up a .emacs file on my new Fedora 20 computer, and get this line when I use emacs -debug-init &. I expect it to be a trivial mistake, but I find the help on this too detailed ...
0
votes
1answer
57 views

Script in C shell skipping over last else statement?

This is a C shell script that checks the number of arguments and if the file/directory exists. When the arguments are valid, it should go to the last else statement and print "hi", but when I run this ...
0
votes
2answers
318 views

System too slow [closed]

My linux system is responding very slowly.I should wait to get the result of my command. How can i investigate to know the problem of his behavior?
2
votes
1answer
190 views

Best practices for maintaining error logs (system, device driver & application)

I have many Pandaboards with Ubuntu armhf and one PC server networked with Wi-Fi. On each embedded board I have a real-time application running constantly. I don't know how to reasonably maintain the ...
8
votes
2answers
1k views

How exactly does printk work internally?

I know printf needs help from the OS to do its job. I also know printf does not work in the Linux source code as there is no library. And so we have printk for debugging. How does printk work ...
2
votes
2answers
59 views

How to tell which files have been created by an application?

I want to find out what files an application has created or modified. In the old days it was easy. cc foo.c created a.out, cc -o foo foo.c created foo, cc -c foo.x created foo.o. Now applications ...
1
vote
0answers
161 views

Why is the service unavailable the second time?

How can this happen? /volume1/homes/me $ tdtool --list /volume1/homes/me $ tdtool -e 44 Learning device: 44 - Could not connect to the Telldus Service /volume1/homes/me $ tdtool --list Error fetching ...
4
votes
1answer
97 views

Methods to diagnose why an application works for local user account but fails on a network user account?

I have setup a CentOS 6.5 machine that is attached to my company's domain. The OS is configured to allow Active Directory authentication so we do not have to have separate usernames and passwords to ...
3
votes
0answers
197 views

Is there an equivalent of addr2line on AIX system?

I'd like to debug proftpd on AIX and according to the documentation, addr2line is a usefull binary to identify what is not working. Extract of proftpd debugging documentation: The key here for ...
2
votes
1answer
1k views

How can we trace problems of crashing programs in Linux?

If an application crashes in Windows we can check the Event Viewer in the Administration tools to see what has crashed. Sometimes it has useful information others not, but it is a start. In linux if ...
1
vote
1answer
430 views

Resolving executable user stack trace addresses in ftrace

I'm trying to obtain a user stack trace in ftrace, but for some reason, only my user program cannot resolve the addresses to symbols. First, the OS I'm using is: $ uname -a Linux mypc ...
11
votes
2answers
1k views

Observing a hard-disk write in kernel space (with drivers/modules)

Apologies in advance if this post is a bit dense/messy, but I'm having a hard time formulating it better... Basically, I would like to study what happens upon a hard disk write, and I'd like to know: ...
2
votes
0answers
374 views

How should I enable the trace log for ALSA hda_unsol_event?

I have reported an ALSA kernel bug and have been asked to "enable tracepoints" and "check the response of hda_unsol_event". I was directed to the kernel docs for instruction, which say: Except ...
1
vote
1answer
538 views

Bash option to get resolved executable path?

Bash is able to trace execution script commands with the -x command line option. Each command is then output to stderr, prefixed by PS4 as stated in the man page. -x After expanding each ...
0
votes
0answers
20 views

Multiply 2 array index variables shell programming [duplicate]

How do i multiply 2 array index variables given the following foo=(1 2) bar=(0.1 0.2) foobar=$((foo[1]*price[1])) # this is wrong echo "$foobar" Current output : 0 Correct/Expected output : 0.4
1
vote
1answer
433 views

what are some of the best resources to learn advanced debugging techniques using gdb? [closed]

I know the basics of how to use gdb. But I would like to learn some advanced debugging techniques using gdb. What are the best resources - books, blogs, tutorials - that any of you use regularly. I ...
1
vote
0answers
226 views

How to trace calls to library from library?

I have an program that calls libcurl, and libcurl calls libgssapi_krb5. If I want to debug calls to libcurl, then ltrace works. But now I want to debug calls to libgssapi_krb5, then ltrace ...
2
votes
4answers
94 views

Is it possible to trace Linux source from initial bootup to desktop-GUI userland code?

I am wondering if, since Linux is 100% open-source, it is possible to follow line-by-line instructions of Linux to observe how the OS works entirely, so that one may get a better knowledge of how OSes ...
1
vote
2answers
794 views

How to “listen” to nginx writes to a file socket

I'm trying to get uwsgi and nginx to play nice. After moving to "file sockets" (hopefully I'm using the right terminology here) from TCP sockets, the only thing I get from uwsgi is a 400 with no ...
2
votes
1answer
326 views

How can I run gdb in one machine and run kgdb kernel in another machine?

I want to run two machine: debugged machine: compiled kernel with kgdb option. debugger machine: for running gdb How can I debug machine 1 from machine 2?
4
votes
2answers
3k views

Install debug flash player in Chrome?

I am trying to adapt the instructions from here, here, and here to install the debug version of the flash player on my Ubuntu 13.04 installation such that Chrome 30.0.1599.66 can use it. ...
3
votes
0answers
121 views

Understanding line numbers reported when using eval

Okay, so I'm stuck working with a shell script that needs to use eval (I know, I know, ultimate evil etc…) however I'm having difficulty debugging some of the line numbers being thrown out by errors. ...
0
votes
1answer
65 views

Getting Sublime + xDebug to work on Debian

I have been trying to get sublime and xdebug to work on debian, but have had no luck. I can't seem to find any debian specific guides. I have tried using the ubuntu based guides, but they don't work ...
1
vote
3answers
128 views

How do I know on which IDE to edit a project's source code?

EDIT: Thanks to all answerers and commenters, there's enough material to keep me busy for a while ! I recently switch to Linux and wanted to do my first development steps with the following ...
5
votes
1answer
3k views

Kernel and QEMU : Unable to mount root fs error

I am trying to run a distro in the virtual disk image with a custom kernel,so that I can experiment and debug the kernel. I followed this to make a disk image and then install Debian to it. Now I ...
2
votes
0answers
682 views

My Debian freezes

I installed a fresh Debian 7 install, but it freezes from time to time, and when it happens (quite often indeed) only the mouse can move around but everything is blocked. All I can do is restart. I ...
1
vote
1answer
239 views

Linux, Debugger program development

We are trying to implement the debugger program which will takes either PID or Program name as input and Invoke the gdb by using PID. Below is two small programs are written, Not able to figure out ...
5
votes
4answers
11k views

How to view core files for debugging purposes in Linux?

I want to view the contents of a core file while debugging a program. How can I view the contents of a core file?
2
votes
1answer
843 views

Debugging dmesg logs

I noticed I have the following in my logs. I just am not sure as to how to go about figuring out how to fix or find out what is causing them and if they are serious. [582046.956291] Core dump to ...
3
votes
1answer
128 views

detect process that executes portscans

I have to administer an ubuntu 12.04 server, where there seem to go portscans to the whole subnet. How can I find out the process that does the scans? pstree init─┬─acpid ...
12
votes
2answers
2k views

Equivalent of “truss -T” and “truss -U” on Linux?

Is there an equivalent of what the -T and -U option of the truss Solaris utility does on Linux. Those are to specify a system call (-T) or library function (-U) which when called by the traced ...