The Tricky.net

The basic commands

It's always difficult for new linux users to find the basic commands, without having all the hundreds of useless options in the syntax.

I try here to summarize the basic and most usefull commands with examples (don't you always look for examples?).

Don't hesitate to leave a comment for any other commands suggestions!

Manage folders and files

cd - Change Directory

move to the specified directory

example :


 

cd /var/logs

 

ls - List the content of the current directory

example :

ls

Just type ls to have a list.

Usefull options

  • Display the details of the files, like date and rights : ls -l
  • Display the hidden files : ls -a

Note you can always combine two options like that :

ls -al

 

mv - MoVe a file or rename it

move a file to another place, OR rename a file. This command will rename a file if both arguments are not path

example

mv myFile.js myNewFile.js

The file called myFile.js will be renamed to myNewFiles.js

If now you specify a path for one of the argument, mv will try to move the file.

example :

mv myFile.js myFolder/myFile.js

Note you don't have to re-type the name of your file, you could write:

mv myFile.js myFolder/

 

mkdir - Make a Directory

create a directory in the current folder.

example :

mkdir myNewDir


rm - ReMove a file or a directory

Removes a single file. You cannot remove a folder with rm, unless you use the option -r (Recursive) : warning, all the files contained by the folder will be removed!

examples :

rm myFile.js

rm -r myFolder/

Usefull options

  • Remove a directory with all its content : rm -r (Recursive)
  • Remove a directory containing read-only files : rm -rf (Recursive and Force removing)

Note that to remove a file beginningwith '-', you cannot escape the name (like "\-myFile.js"), you must write something like:

rm ./-myFile.js

 

cp - CoPy a file or a folder

Copy a file. To copy an entire folder, use the -r option (Recursive)

examples :

cp myFile.js myFile_copied.js

cp -r myFolder/ myFolder_copied/

Useful options

  • Copy an entire folder : cp -r (recursive)

du - Disk Usage

Returns the size in kilobytes of the files or folders given in argument.

examples:

du myFile.html


du -h -s *


Useful options:
  • Human-readable size: du -h
  • Returns size for each folder, and not for each files recursively : du -s

About Searching

Searching for files or text on Linux is very powerfull. Using regular expressions is a considerable advantage.

grep - search text in the given file

grep looks for a given text in all the given file. You can use here the star * to look into all the files of the folder. You can also search in all the subfolders by using the -r (Recursive) option.

example :

grep "I look for you" myTextFile.txt
grep "I look for you" *
grep -r "I look for you" myFolder/
grep -r "I look for you" *
The last example will search in every file of the current folder, and in the subfolders as well.

Note that grep doesn't search in file names! (grep -r "myFile.js" won't return you the path to this file!)

Useful options

  • Recursive search in all subfolders : grep -r note you can also often use the equivalent rgrep
  • Invert the command, look for lines which does not contain the given string : grep -v

 

Combining some commands

Using the pipe (|)

Use the pipe operator to build a "super" command! I explain : imagine you want to search a previous command you typed some time ago, a cp for example. The command history will display a list of the last typed command. How can you now get this list, and then search your command in it ? Here comes the pipe operator into play: you would write

history | grep "cp"
See the trick?

The result of the first command history is given to the second command grep : grep will search in the list returned by history.

Now you can build some super commands, like :

  • searching in search results, i.e. search for multiple terms :
    rgrep "my text" * | grep "my second text"
  • more to come...
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3.23 Copyright (C) 2007 Alain Georgette / Copyright (C) 2006 Frantisek Hliva. All rights reserved."