CNT-2311-Chapter 7 Notes - Revision history

Ande7955: /* System Time */

2011-03-24T10:37:24Z

System Time

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	--UTC or --localtime will tell the hardware clock hold that specific time.		--UTC or --localtime will tell the hardware clock hold that specific time.

			Example

			# date 01011630

			This will set the date to January 1st at 4:30pm

Ande7955 at 10:27, 24 March 2011

2011-03-24T10:27:28Z

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	Example		Example
	#groupadd project3		#groupadd project3

			To delete groups use the groupdel command.

			== System Log Files ==
			The traditional system logger is syslogd, often installed from a package called sysklogd.

			To manually log data you would use the logger command
			the following are syntax used with logger

			-i Records the loggers process ID number

			-s Echos data to a standard error

			-d Causes the logger to use datagrams instead of stream

			-f filename command to log the contents of a file.

			-p pri Speciffy prority.

			== System Time ==
			To set the system time you will have to use the data parameter with a combination of the following syntax

			date [-u\|--utc\|--universal] [MMDDhhmm[[CC]YY}[.ss]]

			By default date assumes you are trying to set local time. If you want to set the universal include the -u or -utc.

			-r or --show will display the set time for the hardware clock

			--set and --date=newdate sets the hardware clock manually

			--systohc sets the hardware clock based on the software clock

			--hctosys sets the software clock based on the hardware clock

			--UTC or --localtime will tell the hardware clock hold that specific time.

Ande7955: /* Groups */

2011-03-24T10:13:02Z

Groups

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	To change from one group to another type newgrp (desired group).		To change from one group to another type newgrp (desired group).

			==== Adding Groups ====
			The groupadd command is used to add new groups

			group [-g GID [ -o]] [-r] [-f]

			-g specifies desired GID

			-r Creates a sub-500 GID

			-f Force creation

			Example
			#groupadd project3

Ande7955: /* Users */

2011-03-24T10:10:04Z

Users

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	First hundred IDs saved for system use.		First hundred IDs saved for system use.

			To remove user accounts use the following userdel commands

			userdel -r causes system to remove all files from user home directory

			userdel -f -r forces the system to remove all files

			To find files owned by a certain User use the find command

			find / -uid 529, this should list all files owned by that UID.

	== Useradd ==		== Useradd ==

Ande7955 at 10:06, 24 March 2011

2011-03-24T10:06:58Z

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	Many passwd parameters can only be run in root.		Many passwd parameters can only be run in root.

			== usermod ==
			Usermod and useradd are very similar, a very noteable difference is that Usermod allows you to edit existing accounts.

			usermod allows -m parameter to be run with -d. This changes a user directory and moves the files to that new directory.

			usermod allows you to change a users login name with the -l parameter, IE usermod bilbo -l bbaggins. bilbo > bbaggins

	== Groups ==		== Groups ==

Ande7955 at 10:02, 24 March 2011

2011-03-24T10:02:20Z

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 -s Sets default shell login for the user.
 Example
@@ Line 33: / Line 35: @@
 # useradd -d /home4/roger -g project4 -G project1, project4 -s /bin/tcsh sally
 # passwd pwnd

Ande7955: Created page with "== Linux Usernames == Consist of any combination of upper and lowercase letters, numbers and many punctuation symbols. User names must begin with a letter and are case sensitive..."

2011-03-24T09:55:38Z

Created page with "== Linux Usernames == Consist of any combination of upper and lowercase letters, numbers and many punctuation symbols. User names must begin with a letter and are case sensitive..."

New page

== Linux Usernames ==
Consist of any combination of upper and lowercase letters, numbers and many punctuation symbols.

User names must begin with a letter and are case sensitive

Usernames may consist of 32 characters but may truncate a username to only 8 characters.

== Users ==
Users are defined not by their name but by a UID (User Id).

First hundred IDs saved for system use.

== Useradd ==

useradd username is the simplest command to add a user.

-c comment parameter passes public information like phone number or real name

-d home-dir specify an accounts home directory

-e YYYY-MM-DD expiration date for the account to be disabled

-f inactive days set the number of day an account is disabled after a password expires

-g default group Set the default group

-G group Adds additional groups, multiple groups can be add with commas.

-s Sets default shell login for the user.

Example

# useradd -d /home4/roger -g project4 -G project1, project4 -s /bin/tcsh sally
# passwd pwnd

== Groups ==
Groups are a collection of accounts mainly for security reasons.

Every file on a Linux system is associated with a specific group and different permissions can be assigned to various members of that group.

Group membership is controlled through /etc/group file.

Each user has a primary group that is set in the /etc/passwd file.

To change from one group to another type newgrp (desired group).