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When You Can't Find Your UNIX System Administrator

When You Can't Find Your UNIX System Administrator

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Table of Contents

What you need to know about this book

Ch. 1. What you need to know about solving problems

Ch. 2. What you need to know about logging in

Ch. 3. What you need to know about running programs

Ch. 4. What you need to know about sharing files

On a UNIX system, your files can be shared with other users.

Security measures make sure that people aren't reading or editing files that they shouldn't be.

Sometimes file security gets in the way of what you want to do.

Each UNIX file has its own distinct set of permissions to define who can read, write, or execute the file.

Each file is owned by a particular user.

Each file is assigned to a particular "group" of users.

Use ls -lg to find out to what group a file belongs.

You can find out to what groups a user belongs.

Each file has three separate sets of permissions: for the owner of the file, the group, and everyone else.

If you don't have read permission, you won't be able to see the contents of the file.

Just because you can read a file doesn't mean that you can change it.

Directory permissions refer to the ability to list the files or create new files.

Use ls -l to learn the permissions on a file.

Use ls -ld to see the permissions for a directory.

If you need permissions changed, you can ask the owner of the file or the system administrator.

The owner of a file can extend read and write permission to all users.

The owner of a file can extend read and write permission to just the group.

The owner of a file can change the group that the file belongs to.

You can also remove permissions.

You can change permissions for all files in a directory.

You can "become" another user to gain their privileges.

Only the administrator can legitimately change the ownership of a file.

If you can read a file but can't write it, you can copy the file and make your changes in the copy.

If you have already made edits when you learn the file is read-only, you can still save your changes.

Sometimes several users have to work on several sets of files at once.

It's dangerous if two people edit a file at the same time.

There are systems for making sure that two people aren't editing the same file.

Quick Reference to file sharing

Ch. 5. What you need to know about printing

Ch. 6. What you need to know about space and time

Ch. 7. What you need to know about everyone else

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Chapter 4. What you need to know about s... > If you have already made edits when you learn... - Pg. 78

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