Console

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Basics of Console Usage

  • If you are new to Linux, as many of us Windows users are, please start by reading the Console section of the FAQ, and then read Terminal Access. They discuss what a console is, how to use SSH, Telnet, and PuTTY, how to get a console and use it, and what are some of the differences between a Windows console and a Linux one.
  • The commands below usually list a usage note, which is a link to a 'man page'. In Linux, man pages describe the syntax of command usage, including all options for the command. Linux splits all of these command line commands into numbered groups, and often lists the group number with the command, eg. cat(1). Ignore the numbers! I think they are just there to confuse those of us who did not grow up speaking Linux.
  • In some commands, you have to press the Ctrl-C keystroke combination to break out. In less, use the q key to quit.
  • When a command produces output that is more than can fit on the physical console, you can use the Shift-PgUp and Shift-PgDn key combinations to page up and down through the console display, including what may appear to have scrolled off the top.
  • The commands below are often compared with DOS or Windows console commands, but even when they appear essentially equivalent, there can be very subtle differences, not necessarily mentioned below.
  • cat - usage and a how to use
    • cat is like the DOS/Windows type, displays a file on screen. The file is assumed to be all text, and if not, will usually display garbage.
    • cat is used often below, but could easily be replaced by more or less (eg. cat /proc/cpuinfo could be less /proc/cpuinfo)
  • more - usage
    • more displays text files like cat, but pages them to the screen. It waits for a keystroke between each page.
  • less - usage
    • less pages text files like more, but also lets you page up and down through them (press q to quit).
  • ls - usage
    • ls is a little like the DOS/Windows dir command, for displaying directories in different ways, but the syntax is very different.
    • ls -l is a common way to list complete directory entries
    • see the Command Macros section for more complex examples
    • Note: in the default setup of unRAID, v is an alias for ls -l, so you can replace the ls -l above with just v. It is OK to use the alias, but it is far better to learn the actual ls -l command in case you are ever in a situation where the alias does not exist. (nearly every other Linux based device will NOT have v as an alias for ls -l, and it may even be aliased to something completely different!)
  • cp - usage
    • cp is like the DOS/Windows copy command.
  • rm - usage
    • rm is like the DOS/Windows del command.
  • cd - usage and a how to use
    • cd is like the DOS/Windows cd command.
    • cd with no parameters changes to the users home directory
  • pwd - usage
    • pwd displays the users current directory
  • mkdir - usage
    • mkdir is like the DOS/Windows md command.
  • rmdir - usage
    • rmdir is like the DOS/Windows rd command.
  • chmod - usage
    • chmod is a little like the DOS/Windows attrib command, but the syntax is very different.
    • The Linux system of security and access attributes is very different to the Windows system. For more help, see this and this.
  • find - usage
    • find is used to search for files
    • Example: the command find . -iname "file*" will search the current folder and all sub-folders for files matching 'file*', using a case-insensitive search.


Console Commands for Hard Drives

The following commands require the Device ID, which you can get from UnMENU (an UnRAID Add On) or the unRAID Web Management page (in UnRAID v4, it is on the Devices tab). Locate your drive, then look for the Device ID in parentheses. It is always 3 lowercase letters, beginning with either hd or sd, eg. sda, sdk, hdc, hdg. For simplicity, sdx will be used below, and you will substitute the appropriate Device ID for your drive. (Extra spaces are added for clarity only, only one space is needed.)

hdparm


To view the identity and configuration information for a drive (at the console or terminal prompt)

hdparm  -I  /dev/sdx


To determine the read speed of a hard drive, the following command can be used. The very last number in MB/sec is the one you want, ignore the rest. Although one run will give you a decent result, for better accuracy, take the average of at least 5 runs. See also Check Harddrive Speed.

hdparm  -tT  /dev/sdx


smartctl


To obtain the SMART info for a drive, including some identity and configuration information, and physical statistics and error history. For more information about SMART and smartctl, see the UnRAID Topical Index, SMART section, also here and here and here and here and here.

smartctl  -a  -d  ata  /dev/sdx

Some newer drives and disk controllers will not issue a report if you use the "-d ata" option, as they are not "ata" drives. (in fact, they will respond with an error message instead) Most older disk controllers did require the "-d ata" option, even if SATA drives. If the smartctl report works without "-d ata" it is OK to leave it off. If you get an error with "-d ata", try without it. The basic command would then be

smartctl -a /dev/sdx


To copy the SMART report to a file called smart.txt on your unRAID flash drive, that you can copy elsewhere and post to the forums, use the following command. Of course, you can change the file name to what ever you like, for example, smart_Seagate320_2008-12-15.txt.

smartctl  -a  -d  ata  /dev/sdx  >/boot/smart.txt

or

smartctl  -a  -d  ata  /dev/sdx  |  todos  >/boot/smart.txt

This second form makes it easier to look at the smart.txt file from a Windows workstation, because it adds the standard end-of-lines that are used in Windows.


To run a short or long SMART test on a drive, select one of the following commands (short test takes minutes, long test can take several hours depending on size of drive)

smartctl  -d  ata  -tshort  /dev/sdx
smartctl  -d  ata  -tlong  /dev/sdx

As of unRAID v4.3 final, smartctl is included with unRAID. Prior to this, it needed to be copied to the flash drive, see this for links to obtaining it. If you had to copy it to your flash drive, then the command to execute would be /boot/smartctl instead of just smartctl. For example, the command to get a SMART report would be

/boot/smartctl  -a  -d  ata  /dev/sdx


other hard drive commands

To view the partitioning of a drive, the drive geometry, and the total number of sectors

fdisk  -l  -u  /dev/sdx


To obtain the total number of sectors on a drive

blockdev  --getsz  /dev/sdx


To verify how the drive is labeled (note the "1" at the end of the command, indicating the first partition on device /dev/sdx)

vol_id  /dev/sdx1


Shows you the drives by their model and serial number and the drive device ID (sda, hdc, etc) linked to each

ls  -l  /dev/disk/by-id
   -or-
ls  -l  /dev/disk/by-id/[au]*  |  grep  -v  part1


Lists the drive devices that have "volume labels", and device ID linked to each. Typically, only the flash drive will have an entry here and it MUST have a volume label of "UNRAID" for unRAID to start up properly

ls  -l  /dev/disk/by-label

Note: in the default setup of unRAID, v is an alias for ls -l, so you can replace the ls -l above with just v.


Console Commands for Networking


Here are a few networking commands that will provide more info about the driver, about the card, about its configured parameters and speed, and about its connection statistics.

Note: The ethtool utility is included in some but not all unRAID distributions. See here for more information about ethtool, and a download link.

  • lsmod - usage
    • lists the installed kernel modules, including your network driver
  • ethtool -i eth0 - usage
    • displays the network driver being used by your network chipset (for eth0), and its version
  • ethtool eth0
    • displays a number of the settings for your network chipset
    • displays the speed setting, typically "Speed: 1000 Mb/s" for a gigabit connection
    • displays the Wake-on-LAN setting, typically "Wake-on: g" if enabled for 'magic' packet
  • ifconfig - usage
    • displays various numeric parameters and statistics for your networking
    • displays your MAC address, as HWaddr
    • displays your local IP, as inet addr
    • displays your MTU setting
    • displays assorted transmit and receive statistics, including errors and collisions
  • ethtool -S eth0
    • displays more detailed network statistics
  • net lookup google.com - usage
    • check for correct nameserver and DNS configuration, should provide the IP for Google if setup right
  • ping -c5 google.com - usage
    • another way to check for correct nameserver configuration (if it times out, or produces errors, you need to set a nameserver)
  • egrep -i "eth0|rc.inet1|((forcedeth|r8169|e1000|e1000e|sky2|skge|tg3|bcm5700|sk98lin)[ :])|dhcp" /var/log/syslog - usage
    • displays lines in the system log (/var/log/syslog) affiliated with networking


Console Commands for System Management

section needs more work
  • tail -f --lines=99 /var/log/syslog - usage
    • Display current end of syslog
    • If you leave the --lines parameter off, it will display the last 10 lines, which is often all you need. There are many situations though where at least a page full is useful, perhaps even 200 (eg. --lines=200).
    • It is essentially real time, use Ctrl-C to quit.
  • free -l - usage
    • Show current memory usage
  • top - usage
    • List processes, with some memory and CPU stats
  • ps -eF - usage
    • List processes (similar to top but ...)
  • ps -eo size,pid,time,args --sort -size (those are commas not periods, double hyphen before sort)
    • List the processes on the server and their memory size (first column) sorted by memory size
  • testparm -sv - usage
    • Show system configuration parameters, including security and permissions
  • w - usage
    • Show who is logged on and what they are doing

For excellent descriptions and examples of the use of screen (usage), see here and here. The screen tool allows you to 'detach' a terminal session, to keep it running even if you log out of the terminal session. An interesting example using screen is in the rtorrent thread.

To cleanly Stop the array from the command line

To cleanly stop the array from the linux command line prior to a reboot requires the use of several commands in turn. They will stop SAMBA, unmount the disks, and then stop the unRAID server. These commands can be performed on the linux command line as follows:

/root/samba stop

Then, for each of your data disks type (note, the command is umount, not unmount. data disk1=/dev/md1, disk2=/dev/md2, etc...):

umount /dev/md1
umount /dev/md2
umount /dev/md3
umount /dev/md4
umount /dev/md5
etc...
/root/mdcmd stop

Note, a disk will not be able to be unmounted if it is busy. It will be busy if it has an open file, or a process whose current directory is located on the disk. If a disk is unable to be unmounted you'll first need to terminate the processes holding it busy before it can be unmounted.

To identify processes holding a disk busy you can type:

fuser -mv /mnt/disk* /mnt/user/*

To terminate processes holding a disk busy you can type (example is for disk1):

fuser -mvk /mnt/disk1

or you can individually terminate individual process IDs by typing

kill PID

(where PID = the numeric process ID as printed by the prior fuser -mv command)
--Joe L. 16:54, 3 January 2011 (UTC)


Console Commands for Files and Folders

Many more file and folder commands can be found in the Basics of Console Usage section above.

  • df - usage
    • reports file system disk space usage
    • example: df /var/log reports space usage of the log folder, in RAM
  • mount - usage
    • mounts file systems; makes your files available!
  • umount - usage
    • unmounts mounted file systems
  • which - usage
    • checks for shell commands that are executable from the system path


Console Commands for System Information

In the commands below, cat is often used to display info, but more and less can be used instead (see Basics of Console Usage section above).

CPU Info

  • lscpu - usage
    • short summary of CPU info
  • cat /proc/cpuinfo
    • much longer report of all CPU's
  • grep --color lm /proc/cpuinfo
    • tests for 64 bit compatibility; if your CPU supports 64bit mode, then 'lm' will be highlighted in the cpuinfo report
  • grep --color vmx /proc/cpuinfo
    • tests for Intel VT CPU Virtualization Extensions; if your CPU supports them, then 'vmx' will be highlighted in the cpuinfo report
  • grep --color svm /proc/cpuinfo
    • tests for AMD V CPU Virtualization Extensions; if your CPU supports them, then 'svm' will be highlighted in the cpuinfo report
  • egrep --color 'lm|vmx|svm' /proc/cpuinfo
    • quick way to test all 3 above (thanks WeeboTech!)


Memory Info

  • free - usage
    • abbreviated summary of general memory info
    • Note: be careful putting much importance on low free memory numbers, as Linux uses memory very differently than Windows
  • free -t
    • summary of general memory info with totals
  • free -mt
    • summary of general memory info with totals, all in megabytes
  • cat /proc/meminfo
    • more complete report of memory usage
  • slabtop - usage
    • displays kernel slab cache information in real time
  • slabtop -s c
    • slabtop display, but sorted by cache size usage
  • vmstat - usage
    • displays virtual memory statistics
  • vmstat -m
    • detailed memory usage


Sensor Info

  • sensors - usage
    • displays some of available sensor info, may include system, CPU, and drive temperatures, system voltages, fan speeds and settings, etc
  • sensors-detect - usage
    • analyses system and displays all available sensors and needed modules, helps configure sensors.conf, requires Perl installed first


Network Info


Other Hardware Info

Note: the following commands may or may not be installed in your release

  • lspci - usage
    • displays information about PCI buses and devices
  • lspci -vnn
    • displays more verbose information about PCI buses and devices (add another v (-vvnn) for even more verbose)
  • lspci -knn
    • displays more information about PCI buses and devices, including device numbers and assigned kernel modules
  • lsscsi - usage
    • displays information about SCSI devices
  • lsscsi -vgl (that's a lower case L)
    • displays more verbose information about SCSI devices, including ATA numbers!
  • lsusb - usage
    • displays information about USB buses and the devices connected to them
  • dmidecode - usage
    • displays the raw information from DMI/SMBIOS tables; may contain info on system manufacturer, motherboard, BIOS, memory, chipsets, etc
    • some of it is not human readable, and it is very often unreliable or wrong
    • if you see Invalid entry length (0). DMI table is broken! Stop., then the DMI tables are bad. Sometimes a BIOS update will improve them, but not guaranteed.


Version Info

  • uname -a - usage
    • displays the Linux kernel version
  • grep "emhttp: unRAID System Management Utility" /var/log/syslog - usage
    • displays the UnRAID version
  • ethtool -i eth0 - usage
    • displays the version of the network driver being used by your network chipset (for eth0)
  • openssl version - usage
    • displays the version of OpenSSL, if installed


Command Macros

Typing commands at the console command prompt can get tiresome, especially when repetitive. You can use the up and down keys to repeat previous commands, or at least reduce the typing, but Linux provides for command macros, otherwise called a command alias. Below is a sample macro file (with the file name of macros) that you can use and modify. It requires being executed from your go file, so insert a line into /boot/config/go similar to /boot/macros.

#!/bin/bash

# set dn like Windows dir/o-d, newest files first
echo "alias dn='ls -Aogt --group-directories-first --time-style=long-iso'">>/etc/profile

# set ds like dn plus Windows dir/s, newest files first, include all subdirs
echo "alias ds='ls -AogtR --group-directories-first --time-style=long-iso'">>/etc/profile

# start tail of syslog with plenty of lines
echo "alias tale='tail -f --lines=200 /var/log/syslog'">>/etc/profile

# an attempt to emulate the old Norton FF (FileFind)
echo "alias ff='find . -wholename '/proc' -prune -o -name '">>/etc/profile

# set screen blanking (if idle for 10 minutes) and monitor to standby (if idle for 30 minutes)
/bin/setterm -blank 10 -powersave powerdown -powerdown 30 

When these macros are added to /etc/profile, they are available in any console you open, whether by SSH or Telnet or at the physical console on the UnRAID machine.

UnRAID already includes one macro - v is aliased to ls -l.