My Scribbles » Linux Command

Changing File Permission and Ownership in Linux

admin — Wed, 24 Mar 2010 06:58:28 +0000

Earlier in this chapter I’ve explained about Basic Linux Commands. Linux, like Unix is a multi-user system and understanding file permission and ownership is one way that the system protects against malicious praud and unathorized access.

How to change the file permission in Linux?
To change the file or folder permission in Linux you’ll need to have better understanding to SSH into your account using PuTTY. Make sure to have root access and sudo privilages to have the full access of the entire system.
Example:
By typing this Linux Command ls -al
You will notice how file being listed and how to interpret it.

d	rwx	rwx	rwx	5	rolan	7055	March 2 2010	html
directory	read, write, execute by the owner	read, write, execute by group	read, write, execute by everyone	links	owner	file size	date	Directory Name

Explanation for drwxrwxrwx
- If any of these letters is replaced with a hyphen (-), it means that permission is not granted for a particular user or group.

- To change ownership on a whole folder and everything inside it you need to use the recursive argument for the chown command. Note the “-R” in the following example.

Syntax: chown -R owner:group foldername or filename

Chown command – Changed the ownership of the file or group.

Type: Sudo chown -R rolan:rolan html cake

Note: html and cake were 2 directories. (-R), Use this syntax to change the ownership of the file or directory recursively.

drwxr-xr-x
= A folder which has read, write and execute permissions for the owner, but only read and execute permissions for the group and for other users.

-rw-rw-rw-
= A file that can be read and written by anyone, but not executed at all.

-rw-r–r–
= A file that can be read and written by the user, but only read by the group and everyone else.

777 is the same as rwxrwxrwx
755 is the same as rwxr-xr-x
666 is the same as rw-rw-rw-
744 is the same as rwxr–r–

- To change the permission of the file to be writable, and readable by anyone.

Syntax: chmod Numeric Permission File or Directory

chmod: The chmod command changes the permissions on the files listed.
Type: sudo chmod -R 777 html

Numeric Permissions:
CHMOD can also to attributed by using Numeric Permissions:
400 read by owner
040 read by group
004 read by anybody (other)
200 write by owner
020 write by group
002 write by anybody
100 execute by owner
010 execute by group
001 execute by anybody
040 read by group
004 read by anybody (other)
200 write by owner
020 write by group
002 write by anybody
100 execute by owner
010 execute by group
001 execute by anybody

Hope you’ll find this helpful.

List of Linux Commands

admin — Thu, 12 Nov 2009 12:33:32 +0000

This topic is the continuation of my previous post. I have explained on How To Use PuTTY SSH Windows. Now, this following Linux Commands probably will help you manage and modify files and permission on your Linux Server.

help command – Display brief info on a bash (shell) build-in command. Just type “help”.

Navigating Files, Folders and Directory using Linux

command	Description
cd -	The cd command allows you to change directories. When you open a terminal, you will be in your home directory.
cd ~/Desktop	To navigate to your desktop directory.
cd /	To navigate into the root directory.
cd ..	To navigate up one directory level.
cd -	To navigate to the previous directory (or back).
cd /var/www	To navigate through multiple levels of directories at once, use cd /var/www, for example, which take you directly to the /www subdirectory of /var.
pwd	“Print Working Directory”. Shows the full path of the current directory.
ls	Lists all the files in the current directory.
ls -al	Lists all files and information.
ls –alR	Lists all files and information in all sub directories
ls *.html	Lists all files ending with .html
ls -d */	Lists all directories within current directory
cd foo	Changes to a new directory, ex. directory name foo.
clear	Clears the screen
vdir	Gives a more detailed listing than the “ls” command

Creating, Moving Directory and File using Linux Commands

Command	Description
mkdir [directory name]	Creates a new directory
mv [old filename] [new filename]	Move/rename a file

Deleting files and Directory using Linux Command

rm -r = (recursive remove) Remove files, directories, and their sub directories. Careful with this command as root–you can easily remove all files on the system with such a command executed on the top of your directory tree, and there is no undelete in Linux (yet). But if you really wanted to do it (reconsider), here is how (as root): rm -rf /*

command	Description
rm [filename]	Deletes a file
rm *.html	Deletes all files ending in .html
rm -r filename.php filename.txt	Removes filename.php and filename.txt files

Copy Files and Directory using Linux Command

The cp command is used to copy files and directories. The copies become independent of the originals (i.e., a subsequent change in one will not affect the other). When a copy is made of a file or directory, the copy must have a different name than the original if it is to be placed in the same directory as the original. However, the copy can have the same name if it is made in a different directory.

cp’s basic syntax:
cp [options] name/filename new_filename

cp -r [directory] [new directory] = Copies a directory and all files/directories in it.
ex. cp -r foo /home/rolan/foo – this will copy foo directory under rolan’s directory.

cp [filename] [new filename] = to copy file in the same directory.

How To Use PuTTY SSH in Windows

admin — Mon, 02 Nov 2009 15:24:21 +0000

It’s been almost a year now since I’m using PuTTY. This is probably one of my favorite tools.

To use Putty, you need to have a basic knowledge in Linux Command. PuTTY allows Windows users to connect to remote systems over the Internet via Telnet and SSH. Both Telnet and SSH allows you to connect to remote systems. This is very useful applications used to secure file transfers over the Internet and it’s hard for others to intercept passwords and other private information.

What is PuTTY and how to use it?

PuTTY is a terminal emulator application which can act as a client for the SSH, Telnet, rlogin, and raw TCP computing protocols. The name “PuTTY” has no definitive meaning, though ‘tty’ is the name for a terminal in the Unix tradition, usually held to be short for teletype.

For Windows and Unix, You can download PuTTY here.

How to use PuTTY with SSH?
here is my guide:

1.) Run the putty.exe file
After you run the PuTTY file this following window will appear on your screen.

On this example, I used “www.example.com” as a Hostname but you can also input directly the IP Address of the Website to connect remotely.

On the Saved Sessions, just type any name that you want (Mine is “Session1″) and then click save to save the Sessions. The next time you connect to your PuTTY, just input the Hostname/IP Address then click the name of the Save Sessions to continue.

2.) After you input all the correct info, click Open button. The following window will appear.

This is the basic knowledge on how to use PuTTY SSH Client. You can start now using some of the basic Linux Command which I’ll be posting here in the coming days, so stay in touch.