Anyway, according to some sources output directed to /dev/console should be shown on the xconsole session This should be especially useful when debugging applications. Presumably, if you know the facility and the priority of the debugging messages, you could direct them through syslog to the console.

Here are some configuration options taken from 'man syslog' to get us pass through:

mail.*;mail.!=info       /var/log/mail - this means that all messages from the mail facility with any priority but 'info' will be logged in the file /var/log/mail

news.info;news.!crit     /var/log/news - all messages from news.info (including) to  news.crit  (excluding)  would be logged to the /var/log/news file.

mail.!debug - putting only this on a line means to skipp all mail messages but the ones for debugging

*.*            @example.org - this means to redirect all messages to example.org

kern.=debug              |/usr/adm/debug - route only kernel debugging messages to the debug pipe

Man sections
1   Executable programs or shell commands
2   System calls (functions provided by the kernel)
3   Library calls (functions within program libraries)
4   Special files (usually found in /dev)
5   File formats and conventions eg /etc/passwd
6   Games
7   Miscellaneous (including macro  packages  and  conventions), e.g. man(7), groff(7)
8   System administration commands (usually only for root)

Man searches the $MANPATH for its entries. Usually these entries are stored in gz format in /usr/man/ (or /usr/share/man/). Uses the $PAGER variable to present the output.

/etc/issue - shows text on console when you log in locally
/etc/issue.net - shows text on console when you log in remotely
/etc/motd - moto of the day - displays on all logins

You can search for help online (stupid):

- The linux documentation project
- Online guides
- Vendor sites
- Mailing lists

/etc/printcap - the file which describes the available printers and their options. Used by the main spooling daemon. Important options:

if=input_filter
lp=printer_device
lf=log_file
mx=max_size
sd=spool_directory

/var/spool/lpd/lpi - the spooling directory for a sample printer called 'lpi'. It contains all the queued print jobs and control files for the lpi printer.

lpq [Options] [Users] [job id]

# lpq -Plpi - show the queued jobs for the lpi printer

lprm [-Pprinter name] [users] [job id] - remove printer jobs

lpc [command] [printer name] [job id] - printing control

# lpc help
Commands may be abbreviated.  Commands are:
abort   enable  disable help    restart status  topq    ?
clean   exit    down    quit    start   stop    up

# lpc topq lpi 102 - move print job 102 to the top of the queue for the lpi printer

# lpc disable lpi - disallow new jobs to be queued for the lpi printer. Allow the ones already queued to be completed.

Here is the ultimate printing command 'lpr -Plpi -J "LPI test print" -#2 -m -p -q -r lpi.txt' - this means to use the printer lpi, to name the job "LPI test print", to make 2 copies of it, send mail upon completion, to make it in Pretty format, to queue it for later and finali to remove the file when done.

lpstat -s = lpstat -d -c -v - Display default printer, all available printers and classes

lpstat -p = lpc status - check printers' statuses

Use cupsenable and cupsdisable to enable and disable a printer.

# lp -i 16 -n 5 - change the number of copies to 5 for job id 16

Filters are used to convert generic data to printable data:
Raw data -> Post Script (PDL format) -> Ghost Script (Printer specific data) -> Printer

To use a Samba printer you need to:
1. use smbprint input filter
2. Have a .config file with in the spool directory defining server, service and password.

CUPS uses MIME types to determine the correct filter for a file.

lpadmin -x [printer name / printer class] - deletes a printer / class.

A printer class is responsible for properly distributing the jobs to a group of printers.

---------------------------------------------------------------------------------------

Ref No: linuxquiz_0047

You might also wonder what means 'quaded decimal netmask in CIDR notation'. If you just take a look at 192.168.0.22/24, it is what /24 stands for Subnetting is more likely the term you are acquainted with and you could easily recall the basic rules from the following chart taken from Wikipedia:

Subnetting

---------------------------------------------------------------------------------------

Another thing that really bothers me is that there is no 'breakfast' time for the 'at' command while there is 'teatime'. This command does take some funky input

---------------------------------------------------------------------------------------
Also, there is one less popular file called /etc/sysconfig/network. I just wonder how could I have missed it until now I guess that's one thing 'setup' changes automatically for you:

NETWORKING=yes
FORWARD_IPV4=yes
HOSTNAME=linux.bgsnow.com
GATEWAY=192.168.0.1
GATEWAYDEV= eth3

---------------------------------------------------------------------------------------

Playing with logger This is another simple program which logs messages to the default syslog file. For example, on my box:

terry@:~$ logger
zaaeeeebi
i am the biggest hacker in the world

terry@:~$

on my other console:

terry@:~$ tail -f /var/log/messages
Oct  6 19:39:41 a2 -- MARK --
Oct  6 19:45:16 a2 kernel: [ 5171.047451] gnome-screensav[593]: segfault at 00000200 eip b7f4cb9d esp bfe87d90 error 4
Oct  6 19:59:41 a2 -- MARK --
Oct  6 20:19:41 a2 -- MARK --
Oct  6 20:39:41 a2 -- MARK --
Oct  6 20:59:41 a2 -- MARK --
Oct  6 21:19:41 a2 -- MARK --
Oct  6 21:39:41 a2 -- MARK --
Oct  6 21:59:41 a2 -- MARK --
Oct  6 22:17:16 a2 terry: asdasd
Oct  6 22:18:11 a2 terry: zaaeeeebi
Oct  6 22:18:20 a2 terry: i am the biggest hacker in the world
Oct  6 22:18:20 a2 terry:

terry@:~$

Probably logger is not the command you are going to use every day but it seems to be quite popular for the LPI 102 exam. Googling for it will render endless number of irrelevant results so you better check its man page.

---------------------------------------------------------------------------------------

Freaking admins with shutdown -k

I guess the inventor of shutdown has a good sense of humor and wants to provide an easy way for the community to freak admins by sending bogus shutdown messages When you have a new admin, make sure he / she is logged on a system and issue:

root@a2:/home/terry# shutdown -k 1 u suck and i 0wn u, little tward. everything is deleted and shutting down!

Broadcast message from terry@a2
(/dev/pts/1) at 22:43 ...

The system is going down for maintenance IN ONE MINUTE!
u suck and i 0wn u, little tward. system is deleted and shutting down!
root@a2:/home/terry#

This is the so called psychological training for new guys to get used to the rough reality It may also help you pass the LPI exam and answer the twisted questions about the shutdown command ))

---------------------------------------------------------------------------------------

Now another funny thing - the well know init command has an option to reload its configuration (don't tell me you haven't reloaded the init configuration without rebouting). It is taken again from PenguinTutor:

Ref No: linuxquiz_0028

What command is used to reload the /etc/inittab file after it has been updated? Choose the most appropriate answer:

/sbin/init q

/sbin/init r

/sbin/init s

/sbin/init 6

Not Answered

Your answer:

No answer

Correct answer:

The correct command is /sbin/init q. The r option is not a valid option for the init command. The s option will change to single user mode, and the 6 option will reboot the system. The option q is the most appropriate as it reloads the configuration file without rebooting the server.

One thing is that according to the only documentation I find 'q' is for quite, suppressing the errors...

oot@a2:/home/terry# init --help
Usage: init [OPTION]...
Process management daemon.

Options:
-q, --quiet                 reduce output to errors only
-v, --verbose               increase output to include informational messages
--help                  display this help and exit
--version               output version information and exit

This daemon is normally executed by the kernel and given process id 1 to denote its special status.  When executed by a user process, it will actually run
/sbin/telinit.

Report bugs to <upstart-devel@lists.ubuntu.com>

Another funny thing is that there are many other undocumented options such as:

root@a2:/home/terry# init a
root@a2:/home/terry# init b
root@a2:/home/terry# init c
root@a2:/home/terry# init d
init: illegal runlevel: d
Try `init --help' for more information.

If you guessed that a, b and c (just like q) did nothing, you guessed it right I hope there is no such a stupid question on the exam

---------------------------------------------------------------------------------------

a. EXT2
b. JFS
c. XFS
d. ReiserFS
e. EXT3

Answer: a and e

Explanation: It might be considered a bug that the latest version of dump can only handle ext2/3  filesystems.

2. Which single command changes the subnet of a network interface?

a. route
b. default
c. netstat
d. ifconfig
e. none of the above

Answer: d. ifconfig allow you to change all parameters of an interface. Here is an example:

ifconfig wlan0 192.168.1.100 netmask 255.255.255.0 broadcast 192.168.1.255

3. Which file system should not be backed up / restored?

a. ext2
b. xfs
c. ext3
d. /home
e. swap

Answer: e. Swap stores temporary information which can be easily recreated.

4. Which directory tree should not be backed up / restored?

a. /tmp
b. /etc
c. /proc
d. /usr
e. /home

Answer: a and c. /tmp stores only temporary files with short life cycle. /proc is dynamically generated by the kernel.

5. What command verifies for syntax errors in /etc/hosts.allow and /etc/hosts.deny?

a. tcpdchk
b. udpdchk
c. netstat
d. iptables
e. setup

Answer: a. tcpdchk checks only for syntax errors the files in question.

6. How can you enable onscreen numbers in a vi (vim) session?

a. set nu
b. se nu
c. set num
d. set +o num
e. set +o nu

Answer: a. and b. It is quite tricky to recognize that set can be used as se for shorter. Unnaturally nu and num are not the same

7. How can you set a user's password invalid after 60 days?

a. passwd -x 60 user
b. passwd -e 60 user
c. chage -M 60 user
d. change -m 60 user
e. usermod -f 60 user

Answers: a. and c. You have to study in details the manuals for passwd, chage and usermod. It is imortant to note the differences between these cases:

- a password expires, the user can log in and change it
- a password has expired and the user cannot log in to change it.

8. What is the binary conversion of the IP address 10.0.15.124?

a. 00101001.00000000.00000001.00011101
b. 00001010.00000000.00001111.01111100
c. 00011010.00000000.00001111.01111100
d. 00011010.00000000.00001101.01111100
e. 00001010.00000000.00001111.01101100

Answer: b. Converting decimals to binary should be quite straightforward. Check this link for help:

http://www.wikihow.com/Convert-from-Decimal-to-Binary

9. The file .rhosts when put in a user's home directory specifies:

a. which remote hosts can log in with the user's username without password
b. which remote hosts are known to the ssh server
c. which remote hosts can be accessed with user's username without password
d. which remote hosts are allowed to connect with the user's username
e. none of the above

Answer: a. The answer is pretty self explanatory. You should know that this option is rarely used nowadays because of security concerns.

10. Which file examines ldconfig for paths to libraries?

a. /etc/ld.so.conf
b. /etc/modules.conf
c. /etc/conf.modules
d. /etc/ld.so.cache
e. none of the above

Answer: a. ldconfig examines /etc/ld.so.conf for all paths to libraries. After that /etc/ld.so.cache is generated.

11. Which command will create / update /etc/shadow to md5 compatible?

a. passconv
b. pwconv
c. mdconv
d. passwd
e. sha1sum

Answer: b. It is important to know that pwconv either creates (if there is no /etc/shadow) or updates the file /etc/shadow with the passwords from /etc/passwd (seconf field on each row). Once the password is converted to /etc/shadow, it is deleted from /etc/passwd (substituted with x).

12. Which command (with exact options) was run to produce the following output?

USER       PID %CPU %MEM    VSZ   RSS TTY      STAT START   TIME COMMAND
root      4366  0.0  0.0   1696   516 tty4     Ss+  13:19   0:00 /sbin/getty 384
root      4367  0.0  0.0   1692   516 tty5     Ss+  13:19   0:00 /sbin/getty 384
root      4370  0.0  0.0   1692   512 tty2     Ss+  13:19   0:00 /sbin/getty 384
root      4371  0.0  0.0   1692   516 tty3     Ss+  13:19   0:00 /sbin/getty 384
root      4372  0.0  0.0   1696   520 tty1     Ss+  13:19   0:00 /sbin/getty 384
root      4373  0.0  0.0   1692   516 tty6     Ss+  13:19   0:00 /sbin/getty 384
root      4965  1.5  3.2  38080 32880 tty7     Ss+  13:19   4:49 /usr/bin/X :0 -
terry     6678  3.5  0.3   5748  3096 pts/0    Ss   18:30   0:00 bash
terry     6708  0.0  0.0   2620  1000 pts/0    R+   18:30   0:00 the_command

Answer: ps au. Make sure you are fully familiar with ps and all of its useful options - from au to auxwf.

13. You wish to copy files overwriting old files. The cp command is aliased with -i (prompt before overwriting). What is the best choice:

a. use cp -f to force to overwriting
b. use the full path to cp /bin/cp to escape the alias
c. use cp -y - to answer yes to all promots
d. use mc
e. first remove the old files and then copy the new ones over

Answer: b . The easiest solution is to use the full path to cp. There is no way to escape the prompts when -i is aliased

14. Which command will show the last kernel messages?

a. dmesg
b. tail /var/log/messages
c. lsmod
d. modinfo
e. none of the above

Answer: a and b. The difference is that dmesg shows only kernel messages, while /var/log/messages may log other things too.

15. When you run 'runlevel', the output is 'N 2'. What does it mean?

a. The current runlevel is 2, there is no previous runlevel
b. The current runlevel is N, the previous runlevel is 2.
c. The current runlevel is N 2.
d. The above output is not possible.
e. There is no such command runlevel.

Answer: a. runlevel specifies first the previous runlevel and then the current runlevel. N means there has been no previous runlevel.

16. Your IP is 192.168.0.15 with netmask 255.255.255.192. Which of the following IPs are not part from your network:

a. 192.168.0.44
b. 192.168.0.18
c. 192.168.0.99
d. 192.168.0.244
e. 192.168.0.2

Answer: c and d. By subnetting 255.255.255.192 defines separate networks with 64 hosts (64=256-192. Of course the first IP is used for the network address while the last is for broadcasts). For self-checking purposes, I recommend using sipcalc, a linux console based IP calculator. Here is how the above can be checked with it:

terry@a1:~$ sipcalc -a 192.168.0.15 255.255.255.192

17. How are you going to flush all pring jobs from all queues?

a. lprm -a all
b. lprm -all
c. lprm *
d. lpadmin --remove-all
e. none of the above

Answer: a. Lprm is not very intuitive so make sure to study its manual in details

18. How are you going to enable traffic forwarding between two NICs in the kernel configuration?

a. echo 'ip_forward=yes' /etc/network/interfaces
b. echo 'ip_forward=yes' >> /etc/modules.conf
c. echo yes > /proc/sys/net/ipv4/ip_forward
d. echo 1 > /proc/sys/net/ipv4/ip_forward
e. It is not possible to change it on the fly. You have to recompile the kernel with this option checked.

Answer: d. The file /proc/sys/net/ipv4/ip_forward is generated by the kernel at boot time but changes are re-read. Make sure 1 is specified there in order traffic forwarding to work.

19. According to RFC 1918, which of the following networks are private?

a. 10.0.0.0 netmask 255.0.0.0
b. 192.168.0.0 netmask 255.255.0.0
c. 191.168.0.0 netmask 255.255.0.0
d. 172.16.0.0 netmask 255.240.0.0
e. 11.0.0.0 netmask 255.0.0.0

Answers: a, b and c. Make sure to note that 172.16.0.0 has a subnet mask which defines as private all IPs from 172.16.0.0 to 172.31.255.255.

20. Which protocol ping and traceroute depend on?

a. TCP
b. UDP
c. ICMP
d. TCP/IP
e. IPX

Answer: ping and traceroute use ICMP - Internet Control Message Protocol defined in RFC 792