/etc/lilo.conf

The LILO bootloader has long been deprecated, in favour of GRUB, however it still has an install base on old systems that remain in production. The /etc/lilo.conf file contains its configuration. After any change in that file, it is necessary to reinstall LILO, by simply running lilo.

Each installed kernel version will have a line in this file, beginning with image=, followed by the path to the kernel file. For example:

image=/boot/bzImage-2.6.28

tailf

tailf does the same thing as tail -f: it displays the last lines of a file, and then follows the file as it grows, and displays new lines as they are appended to it. Compared to tail -f, it uses less resources on the system, by not reading from the disk while the text file is not updated.

See also

enable secret

The enable secret command makes the device ask for a password to allow the user to enter the global configuration mode. Compared to enable password, it has the advantage that it stores the password in the configuration as an MD5 hash, as opposed to clear text.

See also

enable password

The enable password command will make the device ask for a password to allow the user to move up to the global configuration mode. It has the disadvantage of displaying the password in clear text in the configuration. For this reason, is has been deprecated, in favour of enable secret, but still exists in Cisco IOS for compatibility with older hardware that cannot encrypt the enable password.

See also

RHEL

Releases

VersionRelease NotesDownload
7.0 Beta access.redhat.com/site/documentation/en-US/Red_Hat_Enterprise_Linux/7-Beta/html-single/7.0_Release_Notes/index.html (dead link) ftp.redhat.com/redhat/rhel/beta/7/ (dead link)

See Also

Ryzom

Ryzom is a science fiction/fantasy MMORPG, released under AGPL. It is available for Linux, Windows and MAC, and is free to play up to a certain game level.

See also

procmail

Procmail Recipes Syntax

Very briefly:

  • A line starting with :0 denotes the beginning of a new recipe.
  • A line starting with * denotes the definition of a condition inside a recipe.
  • The last line of a recipe is the action. Action lines can begin with:

    • / in which case the email is appended to a text file, mbox-style.
    • | in which case the email is piped to a script for further handling.
    • ! [email protected] in which case the email is forwarded to the email address defined after the !.
    • { which denotes the beginning of a nested recipe.

/etc/pam.d/

Files in /etc/pam.d/ are configurations for PAM stacks. The generic syntax of a line in those files is:

management_group control_flag module [options]

More on management_group and control_flag further in this article. The module is the name of the PAM file to be used. The options are not required, and are either generic ones or module-specific.

management_group

The value of management_group can be one of:

  • auth (for authentication)
  • account (for account management)
  • session (for session management)
  • password (for password managemet)

auth

The auth group is used for user authentication, and is mostly used by tools like login for CLI authentication or XDM or similar for logging in to a desktop environment.

passwd

The passwd group is used for user password management, and is most likely utilized by tools like passwd.

session

The session group manages user sessions. It may verify the existence of a user's home directory or even create it if it does not exist, it can mount partitions that are specific to a user, etc. It will also clean up the user's session after he/she has logged out.

control_flag

The value of control_flag can be one of:

  • requisite
  • required
  • optional
  • sufficient

requisite

The requisite flag makes a check necessary but not enough. This means that a requisite check must succeed for the stack to go on, but the success of the entire stack depends on further checks. In pseudocode:

IF SUCCESS:
    GOTO NEXT LINE
ELSE:
    FAIL

required

The required flag makes a check necessary for the success of the entire stack, while it allows for the execution of the next checks. In pseudocode:

IF SUCCESS:
    GOTO NEXT LINE
ELSE:
    GOTO NEXT LINE
FINALLY:
    FAIL

sufficient

The sufficient flag makes a check stop the execution of the stack if that check succeeds, otherwise execution continues. In pseudocode:

IF SUCCESS:
    STOP STACK EXECUTION
ELSE:
    GOTO NEXT LINE

optional

The optional flag does not affect the execution of the stack, unless the check is the last one in the stack, in which case the success of the entire stack is the same as the success of the last check. In pseudocode:

IF SUCCESS:
    GOTO NEXT LINE
ELSE:
    GOTO NEXT LINE

Note that the pseudocode above does not include the exception that happens when the optional check is that last in the stack.

syslog

syslog facilities

  • auth, a.k.a. security
  • authpriv
  • cron
  • daemon
  • kern
  • lrp
  • mail
  • mark
  • news
  • security
  • syslog
  • user
  • uucp
  • local0 to local7

syslog priorities

A list of syslog priorities, sorted by importance, ascending:

  1. debug
  2. info
  3. notice
  4. warning (previously warn, now deprecated)
  5. err (previously error, now deprecated)
  6. crit
  7. alert
  8. emerg (previously panic, now deprecated)

Send test message to remote syslog server

echo '<12>sourcehost message text' | nc -v -u -w 0 12.34.56.78 514

Source

dhcrelay

dhcrelay acts as a proxy between DHCP clients and a DHCP server, when those are separated by a router, which by default blocks broadcasted DHCP requests. It makes sense to install this on a router between two subnets, only one of which has a DHCP server, or on a relay system, again between two subnets.

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