Basic System Administration

Editing files:

Many editors come with the basic Linux install. Basic console text editors include jed, joe, pico, emacs and vi. (Listed from easiest to most difficult to master) GUI X-window editors (which may be used after X-Windows has started - using the startx command or init level 5) include gedit (Gnome/RH8.0 default), gnp (gnotepad), nedit, editor, edit and xemacs. These editors may be invoked from the command line or from the desktop tollbar. Man pages should be available for the editors. By far the easiest to use is gedit. ("Toolbar Start Icon" + "Accessories" + "Text Editor+")

Linux command shell mode:

By default, when you first log in, the system is in the UNIX command shell mode. After X-windows is started, the GNOME desktop will offer you a command shell by selecting the computer terminal icon on the toollbar. (RH5.2 puts a shell on your desktop by default.) The default shell is bash. For more information type: man bash .

Information, documentation and help:

• Documentation can be found locally in /usr/doc/. (also/usr/doc/HOWTO/) It is easiest to view this with Netscape.
  Beginning with Red Hat 7.1 the documentation is located in directory /usr/share/doc/
• Many commands have a simple help facility built in. Try the --help option. For example try cat --help, ls --help or even man --help.
• Information on a Linux subject or on individual commands is available with the UNIX "man" command. To find commands which refer to a subject, enter man -k <subject>. To view a Linux manual page on a particular command, enter man <UNIX command> . The pages scroll using Page Up/Down keys and arrow keys. To exit type the letter q . Use the command man man for more information.
• /etc/cron.weekly/makewhatis.cron : This sets up manual page index for man -k subject help facility.
  It is recommended that after installation that you execute the script to configure the database rather than wait a week for it to execute automatically. Issue the command (as root): /etc/cron.weekly/makewhatis.cron
• /etc/cron.daily/updatedb.cron : Sets up index for locate command. (Creates data file /var/lib/locatedb)

Security and permissions:

UNIX controls file, directory and device access by user id and group membership. File, directory and device permissions may be granted or denied for reading (r), writing (w) and executing (x). These permissions may be granted to a specific user (u), group (g) or all other users (o). Directory listings can show this with letters representing permissions. For example: -rw-r--r-- which shows that the owner (user) has read and write privileges while the group members and all other users have read only privileges. The symbols display access privileges in the order of owner, group and other. Users are listed in the file /etc/passwd. Groups and group members are listed in the file /etc/group.

See man pages:

• chmod - Change/modify file access permissions.
• group
• ls - list files

Note on root id: The login id root is all powerful and should be used for system administration only. For regular user operation of the system, it is best to create a new user.

All users are a member of a group. New users will be added to a group of the same name as the user (each user had his own group). Membership in other groups may be added. This is often done to give a group of users access to a file or device which is accessible to all group members. See the tutorial on managing groups.

For a complete tutorial on protecting your system while connected to the internet, see the YoLinux.com Internet Security Tutorial.

Device access:

Devices such as diskettes and CR-ROMs are often used by desktop users. It is common to have these devices owned by the groups floppy and cdrom respectively. The device permissions are set such that the device is accessible only by group members. To grant access to a device, add a user to the respective group. Unlike desktop systems, user access to these devices in a server environment is often not a good idea. See the YoLinux.com tutorial Managing Group Access. 

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