Linux check permissions on folder

Last updated on: 2019-03-07

Authored by: Jered Heeschen

This article explains how to use the ls command to check Linux® file permissions. Being able to check the permissions on a file is useful, especially for troubleshooting. You can ensure that a user can read a particular file, for example, or examine a directory structure to ensure that users can follow the hierarchy to the files that they need.

For a more in depth discussion on Linux file permissions, see Linux file permission concepts.

ls command

Use the ls command (the first letter is a lowercase L) to see what files are in a directory. When run by itself, ls returns a list of the current working directory. You can also specify a directory to list. The following example shows a list of the first few files in the /etc directory on a Gentoo system.

The -h option changes the way file sizes are displayed. When you use the -h option, files sizes are displayed in the human-readable format of kilobytes, megabytes, and so on, rather than in raw bytes. Other linux tools such as df also support this flag. The command df -h shows current disk usage in a easier to read format.

To display hidden files (files with names that start with a period), use the -a option. For example, if you use only ls to look at the root home directory on a clean Linux installation, no files are returned:

However, if you add the -a option, the ls command returns a list of files:

Files that start with a period are often system files and application settings files, and you usually don’t want them included in directory lists. But it’s important to know that they’re there and how to see them. The .bashrc file is especially useful to know about because it contains user environment settings that you can change.

If you combine the -a option with the -l option (see the next section) into -la , you get all the details of the hidden files:

Consider the single period and double period in both directory lists:

The single period (.) refers to the directory itself. This is convenient if you want it to run a command and reference your current directory (for example, when you want to copy a file there).

The double period (..) refers to the parent directory. If you type cd .. the directory changes to the one above the one you’re in, in the file system hierarchy. For example, if your current directory is /root , typing cd .. would take you to / , the very top of the hierarchy.

To get more information about the files in a directory, use the -l option with ls, as shown in the following example.

The file names are on the far right side of each line, and the file details precede the names. The necessary details to check file permissions are (1) the series of letters and dashes on the far left of each line, and (2) the two columns that have root in them (in the preceding example). The rest of this article explains how to interpret and use these details.

Permission details

This section explains the series of letters and dashes that define the file permissions.

The first character: file type

In the preceding examples, the first character in each list was either a dash (-) or the letter d .

A dash (-) indicates that the file is a regular file.

The letter d indicates that the file is a directory, which is basically a special kind of file.

A special file type that you might see is a symlink, sometimes called a soft link. It begins with a lowercase L , as shown in the following example:

A symlink is a pointer to another location in the file system.

Permissions abbreviations

Permissions for files are represented by the following letters.

r refers to the read permission.
w refers to the write permission.
x refers to the execute permission.

The permissions characters

Consider the following example:

The first trio of letters after the file type in a file list ( rwx ) shows the permissions for the user , or file owner.

The next trio of characters (also rwx ) shows the permissions for the group category.

The last trio of characters ( r-x ) shows the permissions for the final category, other . In this example, users who are neither the file owner nor in the group have read and execute permissions but not write, as indicated by the dash (-) in the middle position.

Notice the specific order to the permissions in a trio: read, write, execute. A dash in place of a letter for a permission means that category doesn’t have that permission.

The first number

The number listed after the permissions indicates the link count of a file or the number of contained directory entries, for a directory. This number is not relevant for permissions.

Owner and group

After the number of links, two names are listed. In the preceding example, the names are root and mail .

The first name indicates the owner of the file. The user permissions apply to the owner of the file, so in this case, the user ‘root’ has read, write, and execute permissions for this directory.

The second name is the file’s group. The group permissions apply to any user in the same group as the file, so in this case, those permissions apply to anyone in the mail group.

The rest

The remainder of the file details are the size of the file, the date and time that the file was created or last modified, and the file name.

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How to Manage File and Folder Permissions in Linux

For many users of Linux, getting used to file permissions and ownership can be a bit of a challenge. It is commonly assumed, to get into this level of usage, the command line is a must. Although there is always far more power and flexibility to be had, running seemingly complicated command isn’t alwaysa necessity. With the help of some of the most user-friendly desktop interfaces available, you can get away with little to no command line usage. Even with file permission and ownership.

That’s right, much to the surprise of many a new user, managing files and folders can be done from within the file managers. But before we get to the GUI, it’s always best to have a solid understanding of what it’s doing. So, we’ll start with the command line first.

Command line: File permissions

The commands for modifying file permissions and ownership are:

chmod – change permissions

chown – change ownership.

Neither command is difficult to use. It is important, however, that you understand the only user that can actually modify the permissions or ownership of a file is either the current owner or the root user. So, if you are user Bethany, you cannot make changes to files and folders owned by Jacob without the help of root (or sudo). For example:

A new folder was created on a data partition called /DATA/SHARE. Both users Bethany and Jacob need read and write access to this folder. There are a number of ways this can be done (one of which would be to join the users to a special group – we’ll go over managing groups in another post). If Bethany and Jacob are the only users on the system (and you know your network is safe – very important), you can change the permissions of the folder to give them access. One way to do this would be to issue the command:

The breakdown of the above command looks like:

sudo – this is used to gain admin rights for the command on any system that makes use of sudo (otherwise you’d have to ‘su’ to root and run the above command without ‘sudo’)

chmod – the command to modify permissions

-R – this modifies the permission of the parent folder and the child objects within

ugo+rw – this gives User, Group, and Other read and write access.

As you can probably surmise, this command opens wide the SHARE folder such that anyone on the system can have access to that folder. As I mentioned earlier, a more secure method would be to use groups. But we’re just using this for the purpose of demonstration.

The breakdown of permissions looks like this:

The ‘other’ entry is the dangerous one, as it effectively gives everyone permission for the folder/file. The permissions you can give to a file or folder are:

Using the -R switch is important. If you have a number of sub-folders and files within the SHARE directory, and you want the permissions to apply from the parent object (the containing folder) to the child objects (the sub-folders and files), you must use the -R (recursive) switch so the same permissions are applied all the way to the deepest folder, contained within the parent.

Command line: File ownership

Changing the ownership of a file or folder is equally as simple. Say Jacob moved a folder for Bethany into the SHARE directory – but Jacob still has ownership. This can be changed with a simple command:

Let’s break this down.

sudo – admin rights must be used since we are dealing with a folder that belongs to another user

chown – the command for changing ownership

-R – the recursive switch to make sure all child objects get the same ownership changes

bethany – the new owner of the folder

/DATA/SHARE – the directory to be modified

Should Bethany send the folder back to Jacob, the ownership would need to again be changed (again, this will be simplified with the use of groups).

GUI: File permissions

I’m going to demonstrate changing file permissions using the Nautilus file manager on an Ubuntu 13.10 system.

Let’s say you need to allow everyone to gain read/write permissions to the folder TEST. To do this, within the Nautilus file manager, follow these steps:

Open Nautilus
Navigate to the target file or folder
Right click the file or folder
Select Properties
Click on the Permissions tab
Click on the Access files in the Others section
Select “Create and delete files”
Click Change Permissions for Enclosed Files
In the resulting window, Select Read and Write under Files and Create and delete files under Folders (Figure A)
Click Change
Click Close.

The trick comes when you need to change the permissions of a folder which does not belong to you. It can be done, but Nautilus must be started with admin access. To do this, follow these steps:

Open up a terminal window

Issue the command sudo -i

Issue the command nautilus

The sudo -i command gives you persistent access to sudo, until you enter the exit command to remove that access. Once Nautilus is open, you can change the permissions of the folder or file as described above – even if you are not the owner of the folder or file.

NOTE: If you’re using a distribution that doesn’t use sudo, alter the above instructions to:

Open up a terminal window

Issue the command su

Type your root password and hit Enter

Issue the command nautilus.

After you’ve completed the task, close the Nautilus window and then the terminal window.

GUI: Change ownership

Changing the ownership of a file or folder will most often require the use of admin rights. So for this, you’ll need to start Nautilus in the method described above.

For changing ownership of a folder or file through Nautilus, do the following:

In the Nautilus window (opened with admin rights), locate the folder or file in question

Right click the folder (or file)

Click on the Permissions tab

Select the new owner from the Owner drop-down (below)

That’s all there is to it. At this point you shouldn’t have any problems changing permissions or ownership for a file or folder with either the command line or the GUI. The use of groups will empower you to alter permission and ownership with more power and security – we’ll cover that soon. Until then, enjoy modifying your files and folders!

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Linux File Permission Tutorial: How to Check and Change Permissions

Home » SysAdmin » Linux File Permission Tutorial: How to Check and Change Permissions

Linux, like other Unix-like operating systems, allows multiple users to work on the same server simultaneously without disrupting each other.

Individuals sharing access to files pose a risk exposing classified information or even data loss if other users access their files or directories. To address this, Unix added the file permission feature to specify how much power each user has over a given file or directory.

In this tutorial, you will learn how to view and change file permissions in Linux.

How to View Check Permissions in Linux

To start with file permissions, you have to find the current Linux permission settings. There are two options to choose from, depending on your personal preference: checking through the graphical interface or using the command.

Check Permissions using GUI

Finding the file (directory) permission via the graphical user interface is simple.

1. Locate the file you want to examine, right-click on the icon, and select Properties.

2. This opens a new window initially showing Basic information about the file.
Navigate to the second tab in the window, labeled Permissions.

3. There, you’ll see that the permission for each file differs according to three categories:

Owner (the user who created the file/directory)
Group (to which the owner belongs to)
Others (all other users)

For each file, the owner can grant or restrict access to users according to the categories they fall in.

In our example, the owner of the file test.txt has access to “Read and write”, while other members of its group, as well as all other users, have “Read-only” access. Therefore, they can only open the file, but cannot make any modifications.

To alter the file configuration, the user can open the drop-down menu for each category and select the desired permission.

Additionally, you can make the file executable, allowing it to run as a program, by checking the Execute box.

Check Permissions in Command-Line with Ls Command

If you prefer using the command line, you can easily find a file’s permission settings with the ls command, used to list information about files/directories. You can also add the –l option to the command to see the information in the long list format.
To check the permission configuration of a file, use the command:

For instance, the command for the previously mentioned file would be:

As seen in the image above, the output provides the following information:

file permission
the owner (creator) of the file
the group to which that owner belongs to
the date of creation.

It shows the permission settings, grouped in a string of characters (-, r, w, x) classified into four sections:

File type. There are three possibilities for the type. It can either be a regular file (–), a directory (d) or a link (i).
File permission of the user (owner)
File permission of the owner’s group
File permission of other users

The characters r, w, and x stand for read, write, and execute.
The categories can have all three privileges, just specific ones, or none at all (represented by –, for denied).

Users that have reading permission can see the content of a file (or files in a directory). However, they cannot modify it (nor add/remove files in a directory). On the other hand, those who have writing privileges can edit (add and remove) files. Finally, being able to execute means the user can run the file. This option is mainly used for running scripts.

In the previous example, the output showed that test.txt is a regular file with read and write permission assigned to the owner, but gives read-only access to the group and others.

Using Chmod Command to Change File Permissions

As all Linux users, you will at some point need to modify the permission settings of a file/directory. The command that executes such tasks is the chmod command.

The basic syntax is:

There are two ways to define permission:

using symbols (alphanumerical characters)
using the octal notation method

Define File Permission with Symbolic Mode

To specify permission settings using alphanumerical characters, you’ll need to define accessibility for the user/owner (u), group (g), and others (o).

Type the initial letter for each class, followed by the equal sign (=) and the first letter of the read (r), write (w) and/or execute (x) privileges.

To set a file, so it is public for reading, writing, and executing, the command is:

To set permission as in the previously mentioned test.txt to be:
• read and write for the user
• read for the members of the group
• read for other users

Use the following command:

Note: There is no space between the categories; we only use commas to separate them.

Another way to specify permission is by using the octal/numeric format. This option is faster, as it requires less typing, although it is not as straightforward as the previous method.

Instead of letters, the octal format represents privileges with numbers:

r(ead) has the value of 4
w(rite) has the value of 2
(e)x(ecute) has the value of 1
no permission has the value of 0

The privileges are summed up and depicted by one number. Therefore, the possibilities are:

7 – for read, write, and execute permission
6 – for read and write privileges
5 – for read and execute privileges
4 – for read privileges

As you have to define permission for each category (user, group, owner), the command will include three (3) numbers (each representing the summation of privileges).

For instance, let’s look at the test.txt file that we symbolically configured with the chmod u=rw,g=r,o=r test.txt command.

The same permission settings can be defined using the octal format with the command:

Define File Permission in Octal/Numeric Mode

Note: If you need a more in-depth guide on how to use Chmod In Linux to change file permissions recursively, read our Chmod Recursive guide.

Changing User File and Group Ownership

Aside from changing file permissions, you may come across a situation that requires changing the user file ownership or even group ownership.

Performing either of these tasks requires you first need to switch to superuser privileges. Use one of the options outlined in the previous passage.

To change the file ownership use the chown command:

Instead of [user_name] type in the name of the user who will be the new owner of the file.

To change the group ownership type in the following command:

Instead of [group_name] type in the name of the group that will be the new owner of the file.

Learning how to check and change permissions of Linux files and directories are basic commands all users should master. To change file’s group permissions, you might find helpful our article on how to use the chgrp command.

No matter whether you prefer using the GUI or command-line, this article should help you better understand how to use file permissions.

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Linux check permissions on folder