How to Set File Permissions in Linux

How do I change file permissions in Linux using the command line?

To change file permissions in Linux, you can use the `chmod` command followed by the desired permission settings.

For example: If we want to grants read, write, and execute permissions to the owner, and read and execute permissions to the group and others.

chmod 755 filename

Can I change file permissions for multiple files at once?

Yes, you can change file permissions for multiple files simultaneously using wildcards with the `chmod` command.

For instance to sets read and write permissions for the owner and read-only permissions for the group and others for all text files in the directory.

chmod 644 *.txt

How do I change the owner of a file in Linux?

To change the owner of a file, you can use the `chown` command.

For example : If we want to changes the owner to “newowner” and the group to “newsgroup.”

 chown newowner:newgroup filename 

What are the symbolic and octal representations in file permissions?

File permissions can be expressed in both symbolic (e.g., u=rw, g=r, o=r) and octal (e.g., 644) representations. Symbolic representations offer a more intuitive way to specify permissions, while octal representations provide a concise numerical format.

How can I recursively change permissions for all files and directories in a directory?

To change permissions recursively, use the `-R` option with the `chmod` command.

For example : If we want to execute permissions for the owner, read and execute permissions for the group, and no permissions for others, applying these changes to all files and subdirectories within the specified directory.

chmod -R 750 directory

Linux is a multi-user operating system, so it has security to prevent people from accessing each other’s confidential files. When you execute a “ls” command, you are not given any information about the security of the files, because by default “ls” only lists the names of files. You can get more information by using an “option” with the “ls” command. All options start with a ‘-‘. For example, to execute “ls” with the “long listing” option, you would type ls -l . When you do so, each file will be listed on a separate line in a long format. There is an example in the window below.