Troubleshooting
Posted 05-17-2009 at 09:20 PM by David1357
When you are troubleshooting problems with your Linux installation, there are several utilities available that are not obvious to the first time user.
The first thing you will want to have access to during your troubleshooting is something called the "terminal" or the "console" depending on who is doing the speaking or writing. In either case, you should be able to start an instance of the "terminal" by accessing your menu. If you cannot find it, you should be able to get access to your console using [Ctrl][Alt][F1].
Once you have access to a console or preferably a terminal (which will save text that scrolls off the screen), you have many options.
If you are diagnosing a program that crashes, you will first want to run "strace -f <program>". This utility will show you the system call that failed along with the parameters that were passed to it.
If you see an error message involving the word "ioctl", you may have a problem with a device driver. The debug output of device drivers is usually copied to a buffer that can be viewed by running the "dmesg" command. Also, almost all information that is copied to this buffer is appended to a file named "/var/log/messages". You can view this file using "cat" or "less". If you do not have "less" on your system, try "more", its older cousin.
Once you have pored over the output of "strace" and "dmesg", you may still not find the answer you are looking for. However, you will have information that may be useful to people on these forums when they try to help you. Please do not hesitate to paste the entire contents of "strace" or "dmesg" in your post. However, be kind enough to surround the text with "code" tags. If you don't know what "code" tags are, please read the forum FAQ.
David
The first thing you will want to have access to during your troubleshooting is something called the "terminal" or the "console" depending on who is doing the speaking or writing. In either case, you should be able to start an instance of the "terminal" by accessing your menu. If you cannot find it, you should be able to get access to your console using [Ctrl][Alt][F1].
Once you have access to a console or preferably a terminal (which will save text that scrolls off the screen), you have many options.
If you are diagnosing a program that crashes, you will first want to run "strace -f <program>". This utility will show you the system call that failed along with the parameters that were passed to it.
If you see an error message involving the word "ioctl", you may have a problem with a device driver. The debug output of device drivers is usually copied to a buffer that can be viewed by running the "dmesg" command. Also, almost all information that is copied to this buffer is appended to a file named "/var/log/messages". You can view this file using "cat" or "less". If you do not have "less" on your system, try "more", its older cousin.
Once you have pored over the output of "strace" and "dmesg", you may still not find the answer you are looking for. However, you will have information that may be useful to people on these forums when they try to help you. Please do not hesitate to paste the entire contents of "strace" or "dmesg" in your post. However, be kind enough to surround the text with "code" tags. If you don't know what "code" tags are, please read the forum FAQ.
David
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