Chmod 755

[#the-short-answer]The Short Answer[#the-short-answer]

On Linux and Unix-like operating systems (including macOS), the [.inline-code]chmod[.inline-code] command is used to change the read, write, and execute permissions of a file or directory.

Executing the following command:

 $ chmod 755 file.txt

Will give:

• Read, write, and execute permissions to the owner of the file; which is the user account that created the file or has been assigned ownership of the file.
• Read and execute permissions to the group associated with a file; which is a collection of user accounts, such as members of the same team, that have been granted certain permissions on the file.
• Read and execute permissions to the others; which are all other users who are not the owner or members of the group associated with the file.

When using the symbolic notation, the [.inline-code]755[.inline-code] permissions translate to [.inline-code]rwx r-x r-x[.inline-code].

[#chmod-755-on-directory][.inline-code]chmod 755[.inline-code] on a directory[#chmod-755-on-directory]

When applied to a directory as opposed to a single file, these permissions have a slightly different meaning:

• The read permission allows users to list the content of the directory (but only if the execute permission is also set).
• The write permission allows users to create, rename, and delete the entries of the directory.
• The execute permission allows users to enter (or traverse) the directory.

If you want to learn more about file permissions, you can read all about linux/unix permissions.

[#sudo-with-chmod-755]Using [.inline-code]sudo[.inline-code] With [.inline-code]chmod 755[.inline-code][#sudo-with-chmod-755]

The [.inline-code]sudo[.inline-code] command is used to execute a command as the superuser (or root).

Executing the [.inline-code]chmod[.inline-code] command with [.inline-code]sudo[.inline-code] allows you to modify the permissions of a file or directory that you do not have access to as the current user.

For example, you can use the [.inline-code]sudo chmod 755[.inline-code] command on a binary file to give permission to all users to execute it.

 $ sudo chmod 755 script.sh

As another example, you can use the same command on a directory, such as one containing server logs, to give permission to other users to read the logs file.

 $ sudo chmod 755 /var/log/nginx

It is important to note that giving the read and execute permission to all users to a file or directory may lead to security vulnerabilities, especially if it contains sensitive information or has the ability to execute arbitrary code.

If you want to learn more about the [.inline-code]chmod[.inline-code] command, you can read about the chmod command more broadly.

[#chmod-755-vs-chown-755]The difference between [.inline-code]chmod 755[.inline-code] And [.inline-code]chown 755[.inline-code][#chmod-755-vs-chown-755]

Often mistaken for each other, [.inline-code]chmod[.inline-code] and [.inline-code]chown[.inline-code] are two different commands that serve a distinct purpose.

The [.inline-code]chmod[.inline-code] command is used to change the permissions of a file or directory, while the [.inline-code]chown[.inline-code] command is used to transfer the ownership of a file or directory to another user or group.

Since the [.inline-code]chown[.inline-code] command allows you to either use symbolic names (e.g. foobar) or identifiers (e.g. 1001) to specify the user or group you want to transfer the ownership of a file to, you have to make sure not to mistake them with numeric permissions, such as the ones used with the [.inline-code]chmod[.inline-code] command.

For example, this command will change the permissions of the target file:

 $ chmod 755 file

While this command will transfer the ownership of the target file to the user identified on the system by the UID 755:

 $ sudo chown 755 file