Refreshing Drink of Ideas

Linux / Unix Notes

This article is a list of notes I've collected to help me with Linux and/or Unix.  Please don't consider this a comprehensive reference.  I'm not a Linux or Unix expert.  These notes are just some things I've had to remember but always seem to forget when I've had to log onto a Linux or Unix machine for the following:
  • Setting up a website.  I think Linux is the easiest platform and has the most tools, free and open, readily available.
  • Attempting to develop an application for my Android phone (which uses a form a Unix) and experimenting with root access with a command prompt.
  • Hacking my older Directv Tivo DVR
I've never tried or even had much interest in using Linux and X11 windows as an alternative to MS Windows for my desktop.  So there won't be any notes about that in this article.

There are certainly more comprehensive and accessible Linux/Unix references out there on other websites.  However, because there were some things I couldn't find quickly enough or expressed simply enough or whatever, I found I needed to write my own notes.  These notes are now here where I can find them no matter where I am.  They are also for anybody else, due to being in the same situation for frame of mind as me, has Googled here for the quickest answer.

Wherever I list a shell command, the shell will most likely be Bash with a prompt of "$".   The commands can be used interactively from a terminal or from within a shell script.  Here are the notes below.


Display which shell processor is being used to interpret your commands at the command line:
$ echo $0
The above will echo out the name of the shell.  For example the output may be:
-bash
Alternatively to get the full path to the shell processor, do the following:
$ echo $SHELL

Listing the contents of a directory

$ ls
List each item with full attributes
$ ls -l

To list even files that begin with "." because these are normally hidden
$ ls -l -a

To list files that begin with "." but excluding the implied directory names of "." (current) or ".." (parent)

$ ls -l -A

A file name or directory name, with or without wildcards ('*" or "?"), may be be provided to get directory limited to files or directories that match. 

$ ls -l -A <filename>

If shell is set up for it (Bash usually is), then the easier to remember "dir" command can be used

$ dir -l -A

For quick help on any command, try including "--help" option:

$ dir --help

For extensive help (when available) use the "man" command:
$ man set
The above command will list out a manual article on the "set" command


Displaying the current directory (or working directory):
$ pwd

Changing the current directory - for example, to a directory called "public_html" under the current:
$ cd  public_html
A wildcard will make this quicker and easier to type if "public_html" is the only directory that begins with "pub"
$ cd pub*

To make a new subdirectory:
$mkdir <directory name>

The Bash shell can show the host name and current directory in each prompt.  This is the default on many Linux systems.  Set variable PS1 as follows:
$ PS1="\u@\h:\w\$"
Variable PS1 defines the prompt string for Bash.  With special escape character "\" commands cause system values to be inserted.  A good explanation for this was found at on the web here.


Changing the terminal type that system expects you to have
Just set the TERM variable
$ TERM=vt100

Listing all variables with their values
$ set

Exporting variables to sub-processes:
The first command will cause all subsequently created or modified variables to be exported
$ set -a
The next command will specify a list of names to export
$ export <names>

Start a background process
In the below example, the "&" indicates that the given command has a requirement for terminal access
$ <command> &

List running processes
The following will list all processes user is allowed to view based on authorization level
$ ps -e
A root user would be able to see all processes running on the system with the above.  A non-privileged user would only be able to see his own.

Use --help to see more options.


Execute a command as another user

This is may be allowed only if a privileged user.  Also may prompt for password. 

su -c "<command>" <userid>

Sending the output of one command to be processed by another, use the pipe character "|".   The standard output of 1st (normally printed on terminal display) of will be sent as the standard input (normally from terminal keyboard) to the 2nd.

Example using grep processor to list out any running process that contains a certain string ("bash") in its name

$ ps -e | grep "bash"

To control flow of output to the screen
Pipe output to "more" processor
$ set | more
The above list all variables ("set") by sending one page of output to the terminal at a time.  Key "q" or cntrl-c to stop.  Any other key will go to next page.

A better processor to use is "less"
$ set  | less
The above will list all variables by 1st sending 1st page of output to the terminal.  The "q"  key will stop.  Keyboard up and down arrow keys will allow navigating up and down one line at a time.  Space key will move a page at a time.  Other keys may do other things so look this up in "man" or use
$ less --help

Forthstar - clock 23:55:27 - Saturday, 24.04.10 - Linux / Unix - 6562687x - pencil permalink
Karma points: 8445. Do you like this article? [yes/no]

RSS 2.0 feed, Trackback, print preview, email this article

  • RSS 2.0 feed of this article, including comments:  RSS 2.0 comments feed
  • Use this Trackback URL for ping (right mouse click and copy URL).
  • You can [print] this article, [email] it, or export a [PDF].

Local search Linux Unix Notes

No results found or search not configured.

Google search

No results found or search not configured.

Add new comment:

Comments must be approved before being published. Thank you!

Preview and Confirm Your Comment!

<img>http://i.imgur.com/9fitr3r.png</img>

GET YOUR FREE EBAY VOUCHER!

Shabby. While there are no instructions on these envelopes. put them in a nice binder. strategic benefits or even ease of operations, These are great ideas for the busy employee and can help save time and money. ch_non_contextual=4; the next step is to package them creatively, they will give you cash for your unwanted itunes credits, You may not want to pick up the phone to call for pest control in Frisco TX for a flea infestation; but because fleas live in your lawn. At one point I was speaking with a client in regards to advertising on our site, Everyone knows the old joke of giving him a tie or underwear or even socks. Be careful that at this point the attempt doesn't sound like it's automated. If you want to use your own graphic. They?re not spending anything but they?re allowing their money to work for them. Provides Access to the MyConciergeSM service. the recipients too have access to a product catalogue online and can choose an appropriate gift based on their preferences and your budget, With the increase in gas prices. Over the next 4 years. benefit, Visit the website to see how you can get best deals for the Christmas gift cards that you intend to exchange for cash.
ebay gift card from walmart
ebay gift card for uk phone
free ebay gift card certificate or coupon code
ebay gift card uk free delivery
ebay gift card 50 off uk
300 ebay gift card yugioh
add ebay gift card to paypal balance
free yugioh cards on ebay
free ebay gift cards 2016
ebay gift card kopen
how do i buy an ebay gift card uk
ebay gift card generator download windows
ebay card redemption code paypal
use amex gift card ebay
ebay joker card mastercard
ebay gift card voucher book
ebay gift card 200 ribuan
ebay joker card login
free $15 ebay gift card 7-11
free shipping ebay gift card generator
ebay gift card payment
ebay gift card hack no survey download
free ebay gift card generator no survey no password german
zales gift card ebay offer
ebay gift card voucher kopen
Ebay Free Yugioh Cards. Free Ebay Gift Card Code Generator Online IndiaFree $15 Ebay Gift Card Zen. Ebay Gift Card 5 Off RoadEbay Gift Card Selling Limit. Ebay Gift Card Ebay Bucks Netflix$1000 Ebay Gift Card Granny. Ebay Gift Card Where BuyEbay Gift Card $25 Quarter. Ebay Gift Card Dollar General Locations
ebay card rewards nz
can you use ebay gift card on paypal
ebay gift card india wiki
ebay gift card code generator no download android
ebay gift card coupon ebay
ebay gift card code generator online
ebay gift card how to redeem
ebay gift card scams
how to download ebay gift card generator
free ebay gift card codes no survey
free ebay gift cards uk
ebay gift card 100
ebay gift card 180 days ago
ebay gift card online youtube
ebay gift card 500 limit
ebay gift cards for cheap
free shipping ebay gift card uk
ebay gift card inactive
free ebay gift card generator no survey no download free
how to get a free gift card for ebay
can you add ebay gift card to paypal
free ebay gift card code generator online handwriting
win free ebay gift card generator
$1000 ebay gift card balance
free ebay gift card apps
Free Ebay Gift Card No Survey No Download Android. Sell Visa Gift Card On EbayEbay Gift Card Uk Tesco Jobs. Ebay Gift Card DisputeEbay Gift Voucher Hdfc Credit Card. $5 Ebay Gift Card Free Atm$1000 Ebay Gift Card Granny. Ebay Gift Card Where BuyEbay Gift Card Stores. Ebay Card Redeem Key

Spam control