What does chmod do

The chmod command in the Linux operating system and other UNIX-like systems is used to change access rights to files and directories. Access rights determine which operations are allowed for a particular file or directory, such as reading, writing, and executing.

What allows you to do?

Using the chmod command, you can change access rights for the file owner, group, and other users. Access rights can be set as numeric values or symbolic modes.

This is how rights change:

To remove the executable flag, use the -x option:

For example, to set the read, write, and execute rights for the file owner, but only read rights for the group and other users, you can use the following command:

chmod 755 filename

where "filename" is the name of the file or directory for which you want to change access rights.

How to install chmod

To install chmod, run the following command in the terminal:

chmod <access rights> <file or directory name>

where:

<access rights> - numeric value or character mode that defines the necessary access rights. Numeric values can be from 0 to 7, where each digit corresponds to certain access rights (4 - read, 2 - write, 1 - execute). Character modes consist of a combination of the letters "r", "w" and "x" for different categories of users (owner, group, others).

<file or directory name> is the path to the file or directory for which you want to change access rights.

Examples of using the chmod command:

Set the right to read, write and execute for the file owner, and read-only for the group and other users: chmod 755 filename
Set the right to read and execute for the file owner and group, and read-only for other users: chmod 554 filename
Set the right to read and write for the file owner and the group, and read-only for other users: chmod 664 filename
Set the right to execute for all users: chmod +x filename
Set the read and write permission for the file owner: chmod u+rw filename
Set the right to execute for the group and other users: chmod go+x filename

The chmod command cannot be deleted, as it is a built-in command in most UNIX and Linux operating systems. However, you can change the file or directory permissions back to the default values if that's what you want to do.

To return access rights to a file or directory to the default values, you can use the chmod command with the corresponding numeric values or character mode. For example, to set access rights 644 for a file, you can run the following command:

chmod 644 filename

This will set read and write permissions for the file owner, and read-only permissions for the group and other users.