What does the ‘chmod 755 file’ command accomplish?

The command ‘chmod 755 file’ sets specific permissions for the file owner, group, and others based on the numerical mode provided. In this case, the number 755 is broken down as follows:

• The first digit, 7, represents the permissions for the owner of the file. In octal notation, 7 corresponds to read (4), write (2), and execute (1) permissions combined, giving the owner full access.

• The second digit, 5, represents the permissions for the group. The number 5 corresponds to read (4) and execute (1) permissions, allowing group members to read and execute the file, but not to modify it.

• The third digit, also 5, applies the same permissions to others. Here, others have read (4) and execute (1) permissions as well.

Therefore, the command effectively grants the file owner full permissions (read, write, and execute), while granting read and execute permissions to the group and others. This structure is commonly used for scripts and executables that should be accessible to all users but should not be modified by them.