Introduction to Basic Troubleshooting Terminal Commands in Ubuntu Linux

Table of Contents:

1. Introduction
2. Examples of basic troubleshooting commands within Terminal and how to use them
3. A list of basic troubleshooting commands and their function within Ubuntu Linux

Introduction

The following article deals with basic troubleshooting commands in terminal on an Ubuntu operating system.

The most common ways of opening a Terminal window in Ubuntu Linux are:

• Use the desktop search function to look for terminal, command, or prompt and it brings up the Terminal window as a search result.
• If you use the menus to locate it, most versions of Linux put it in the same location as the other application launchers.
• The following keyboard shortcut works across most Ubuntu revisions, and the other types of Linux. Press the CTRL + Alt + T keys down simultaneously.

See the following article if you are looking for a tutorial on general terminal commands:

• How to use the Ubuntu Linux Terminal on your Dell computer

See the following reference article if you were after a list of the most common commands:

• A guide to Ubuntu Linux Terminal Commands for your Dell computer

Examples of basic troubleshooting commands within Terminal and how to use them

This list provides basic Terminal commands within Ubuntu Linux. It gives examples of how they can be used to help troubleshoot specific issues with your computer.

• Use the command uname to show what kernel is being used. The kernel is the first section of the operating system to load into memory. It controls such system areas as disk drive management, memory allocation, system processes, and interrupt handler. In the example below, the kernel being used is 3.11.0-15-generic:

  user@avalon:~$ uname -a

  Linux avalon 3.11.0-15-generic #23-Ubuntu SMP Mon Dec 9 18:17:04 UTC 2013 x86_64 x86_64 x86_64 GNU/Linux

  user@avalon:~$

• Use the command dmesg to show the contents of the boot log. This is a good way to find errors at startup:

  user@avalon:~/linux101$ sudo dmesg > dmesg.log

  In the example below, the command cat can be used with dmesg to join the contents of the log file. The additional command grep can be used to show any instance of a particular file name occurring in the log, for example, either Intel or error:

  user@avalon:~/linux101$ cat dmesg.log | grep intel

  [ 1.732400] intel_idle: MWAIT substates: 0x21120

  [ 1.732402] intel_idle: v0.4 model 0x3A

  [ 1.732405] intel_idle: lapic_timer_reliable_states 0xffffffff

  [ 10.148411] fbcon: inteldrmfb (fb0) is primary device

  [ 10.922434] i915 0000:00:02.0: fb0 inteldrmfb frame buffer device

  [ 10.926448] snd_hda_intel 0000:00:1b.0: irq 50 for MSI/MSI-X

  user@avalon:~/linux101$

  user@avalon:~/linux101$ cat dmesg.log | grep error

  [ 7.478502] EXT4-fs (sda2): re-mounted. Opts: errors=remount-ro

  user@avalon:~/linux101$

• The command lspci lists all devices that are found on the Peripheral Component Interconnect (PCI) bus:

  user@avalon:~/linux101$ sudo lspci > lspci.log

  Using the lspci command with the additional commands of cat and grep helps to isolate specific PCI devices, as with Realtek below:

  user@avalon:~/linux101$ cat lspci.log | grep Realtek

  07:00.0 Ethernet controller: Realtek Semiconductor Co., Ltd. TRL8111/8168/8411 PCI Express Gigabit Ethernet Controller (rev 07)

  09:00.0 Unassigned class [ff00]: Realtek Semiconductor Co., Ltd. RTS5209 PCI Express Card Reader (rev 01)

  09:00.1 SD Host controller: Realtek Semiconductor Co., Ltd. RTS5209 PCI Express Card Reader (rev 01)

  user@avalon~/linux101$

• Use the command lsmod to list all the loaded mod files within the kernel:

  user@avalon:~/linux101$ sudo lsmod > lsmod.log

  user@avalon:~linux101$

  In Linux, the driver files are loaded as mods. To see which drivers or mods are loaded in the kernel, you can use the cat and grep command. When used with lsmod to search for specific mod files, you can see two examples with Dell and hda below:

  user@avalon:~/linux101$ cat lsmod.log | grep dell

  dell_wmi 12761 0

  sparse_keymap 13948 1 dell_wmi

  dell_laptop 17369 0

  dcdbas 14847 1 dell_laptop

  wmi 19070 1 dell_wmi

  user@avalon:~/linux101$

  user@avalon:~/linux101$ cat lsmod.log | grep hda

  snd_hda_codec_hdmi 41117 1

  snd_hda_codec_realtek 55704 1

  snd_hda_intel 48171 3

  snd_hda_codec 188738 3 snd_hda_codec_realtek,snd_hda_codec_hdmi,snd_hda_intel

  snd_hwdep 13602 1 snd_hda_codec

  snd_pcm 102033 3 snd_hda_codec_hdmi,snd_hda_codec,snd_hda_intel

  snd_page_alloc 18710 2 snd_pcm,snd_hda_intel

  snd 69141 17 snd_hda)codec_realtek,snd_hwdep,snd_timer,snd_hda_codec_hdmi,snd_pcm,snd_seq,snd_rawmidi,snd_hda_codec,snd_hda_intel,snd_seq,device,snd_seq_midi

  user@avalon:~/linux101$

• Use the command lsusb to list all the USB devices that are connected to the USB bus:

  user@avalon:~/linux101$ sudo lsusb > lsusb.log

  user@avalon:~linux101$

  You can use this command with the additional cat and grep commands to isolate specific USB devices, as with Intel below:

  user@avalon:~/linux101$ cat lsusb.log | grep Intel

  Bus 002 Device 003: ID 8087:07da Intel Corp.

  Bus 002 Device 002: ID 8087:0024 Intel Corp. Integrated Rate Matching Hub

  Bus 001 DEvice 002: ID 8087:0024 Intel Corp. Integrated Rate Matching Hib

  user@avalon:~/linux101$

• Use the ifconfig command to set and query your computer's network settings:

  user@avalon:~/linux101$ ifconfig > ifconfig.log

  user@avalon:~/linux101$

  You can use this command with the additional cat and grep commands to search for inet, which lists your computer's IP addresses:

  user@avalon:~/linux101$ cat ifconfig.log | grep inet

  inet addr:127.0.0.1 Mask:255.0.0.0

  inet6 addr: ::1/128 Scope:Host

  inet addr:192.168.1.90 Bcast:192.168.1.255 Mask:255.255.255.0

  inet6 addr: fe80::caf7:33ff:fedb:b2bc/64 Scope:Link

  user@avalon:~/linux101$

A list of basic troubleshooting commands and their function within Ubuntu Linux

The following table lists the more basic commands that are used within Linux for troubleshooting purposes. It gives the function and syntax for each:

For additional help troubleshooting your Dell computer, you can contact us from Dell's Support Website.