Tag Archives: Gnu

Advanced use of – Find -: a handy command line tool for Linux

This post is basically directed towards new users of Linux which are not much familiar with command prompt. This is a small but comprehensive article about ‘GNU find’ .
Find Your Lost Files!
Let’s start from a simple example:
Suppose you want to search for a file named ‘master.txt’ in your home directory.
Open the Terminal and issue the following command:
find . -name “master.txt”
‘find’ will immediately show the results. If ‘find’ does not show any result, this means that the file, in our case, ‘master.txt’, does not exist. It is not always the case that you want to find something in you home directory. The lost/desired file may be anywhere in your computer. Suppose you want to find a file named ‘space-01.jpg’ and you only know that is located somewhere in /usr directory. You can find it by issuing following command in Terminal:
find /usr -name “space-01.jpg”
and ‘find’ will tell you that this is located under /usr/share/backgrounds.
Using Wildcards
Maybe you want to search for a file but you don’t know its exact name? Don’t worry! You can still locate the file using ‘GNU find’ and wildcard will help you in this regard. Wildcards are a way of searching files when you don’t know much about your desired file.
One of the commonly used wildcard is asterisk (*). Lets consider an example to better understand the things.
Suppose you want to search a file named ‘Jumping_Flowers’ but you only remember the ‘Jumping‘ part of the file name. So issue the following command in Terminal:
find . -name “Jumping*”
And it will display all the files starting with the word ‘Jumping’. You can use asterisk (*) anywhere with a file name. For example:
find . -name “*Jumping*”
And it will display all the files which contain the word ‘Jumping’.
Here are some more examples of use of a wildcard:
find . -name “Jumping*Flowers*”
find . -name “*Jumping*Flowers.mp3”
Searching For Different File Types
Sometimes you are not looking for some specific file but you are looking for a group of files. For example, you may be looking for all the .txt files in your home directory. To find all the .txt files, you will give the following command in Terminal:
find . -name *.txt
In case of mp3 files, the above command will be:
find . -name *.mp3
When You Want to Search with Respect to Time
If you want to search for files by the last time they were accessed, you can use -amin flag with ‘find’. In this case you have to put a minus (-) sign before the time. The time here is in minutes. In order to search for .doc files which were accessed in last 10 minutes, you will give the following command:
find . -amin -10 -name “*.doc”
Similarly, to search for .doc files which were modified in last 20 minutes, you will use -mmin option as follows:
find . -mmin -20 -name “*.doc”
Search For Files which are Eating Your Hard Disk
There may be files on your system which are not only huge in size but also located obscure places. You may also may not know when they were last accessed. You have to use -size option with ‘find’ to locate them.
Let’s see how we can do this:
find . -size +100M
It will list all those files which are greater than 100 Megabytes. You can replace ‘M’ with ‘G’ (for Gigabyte) or with ‘k’ (for Kilobyte)
Copy, Move, or Delete Unwanted Files on the Fly
Copy – ‘find’ can also be used to copy or backup your files. You can use ‘find’ to copy certain files from one location to other with one simple command.
Suppose you want copy all of your mp3 songs from your home directory to your Windows Partition. Enter the following command in Terminal:
find . -name “*.mp3” -exec cp {} /path/to/Windows_Drive \;
And all of your mp3 files will be copied to the desired Drive/Folder.
Move – There may be situations that you quickly want to move all of your document files from your Hard Disk to your USB to keep them safe. To move all of your documents from your home directory to your USB, you will issue the following command:
find . -name “*.doc” -exec cp {} /path/to/USB \;
Delete – Suppose there are a lot of .tmp files and you want to get rid of them at once. Again ‘GNU find’ is at your service and does the work for you. Issue the following in Terminal and all of the .tmp files are gone…
find . -name ‘*.tmp’ -exec rm {} \;
Which Files are Owned by You and Which Are Not?
There may be a situation when you want to know that which files in some other directories (or even in your home directory) are owned by some other user of your computer.
Suppose there is another user named ‘blackstar’ with whom you are sharing your PC. Now you want to know that which .doc files in Windows Directory is owned by this user ‘blackstar’. You can do this by issuing the following command:
find /path/to/Windows_Drive -user blackstar -name “*.doc”
Just replace ‘blackstar’ with your username to search on your system.
Direct the Output of ‘find’ to a File
You can save the results of your ‘find’ command to a text file which will allow you to examine the results in detail at some later time (or to create playlist of your songs). For this purpose a greater than (>) sign is used (referred to as “piping the command”).
Suppose you want to save the list of all the mp3 songs in your home directory to a text file (which you can later share with your friend), you can do this by:
find . -name “*.mp3” > mp3.txt
It will save the complete path to all of your mp3 songs in the file named mp3.txt.

Create ‘alias’ (shortcuts to commands) using Linux Sophisticated Commands

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Long sophisticated instructions are usually not solely tough to recollect but in addition take a lot of time to be typed. When it’s a must to use them on day by day foundation, you turn into annoyed when typing them repeatedly and again… So, ‘alias’ are extra appropriate for lengthy and complex commands.

Let’s think about an example.

To find the top 10 largest files in your system, you can set the next ‘alias’:

alias top10files=”find . -type f -exec ls -sh {} \; | sort -n -r | head -10”

You can even combine different instructions with ‘alias’. As an illustration, if you happen to often use ‘tail’ and direct its output to file to later view that file, you may set a very simple ‘alias’ to do this cumbersome operation in 1 word:

alias Tail=”tail /var/log/messages > hello.txt;cat hello.txt”

Now just enter ‘Tail’ and voila! All is done at once.

You need to use any file with tail and direct its output and you’ll even use ‘nano’ or ‘vi’ to view/edit its output.

Here’s one other example… ‘alias’ to connect to a remote server:

alias any_name=”ssh -l -p ”

You possibly can even create ‘alias’ on your bash scripts, like:

alias clc=”sh /home/user/myscripts/calc.sh”

Now that you have set a number of totally different ‘alias’ you may want to test that which ‘alias’ are set in your system. To do that, simply difficulty the next command:

alias

and it will list all the set ‘alias’ you have.

To remove an ‘alias’, just issue the ‘unalias’ command, like:

unalias Google

and now typing Google in Terminal will do nothing (as it was set with lynx).

To remove all the ‘alias’, issue the following command and all the ‘alias’ are gone:

unalias -a

We have mentioned the way in which of setting the ‘alias’ for different sorts of commands. However setting ‘alias’ in this approach be temporary. While you reboot you PC, all the ‘alias’ which you will have set will probably be gone. This does not mean that it’s a must to set all of the ‘alias’ each time you boot your PC. You probably have set an ‘alias’ and you favored it a lot that you really want it to completely reside in you PC, simply add this alias in ‘.bashrc’ file in you dwelling directory. For example, if you would like ‘alias’:

Set up <software_name>

to permanently reside in your PC then user your favorite text editor and add the following line in your ‘~/.bashrc’ file:

alias Install=”sudo apt-get install”

Now this ‘alias’ will not vanish into thin air when you reboot your PC. Only those ‘alias’ which are listed in ‘~/.bashrc’ file will be permanent.

This information is just a preview about ‘alias’. It’s just about primary ways of using ‘alias’ to make your life simpler. ‘GNU alias’ is a instrument which can simplify your life immensely. But sadly this device isn’t given the attention it deserves. Briefly, it is such a strong tool that when you give it proper time, it could possibly make you overlook typing.