Sunday, May 20, 2007

The Ultimate Linux Reference Guide for Newbies

FILE AND DIRECTORY BASICS This cateogry also includes utilities that change file/directory properties and permissions
ls List files/directories in a directory, comparable to dir in windows/dos.
ls -la Shows all files (including ones that start with a period), directories, and details attributes for each file.
cd Change directory (e.g cd /usr/local/bin)
cd ~ Go to your home directory
cd - Go to the last directory you were in
cd .. Go up a directory
cat Print file contents to the screen
cat filename.txt Print the contents of filename.txt to your screen
tail Similar to cat, but only reads the end of the file
tail /var/log/messages See the last 20 (by default) lines of /var/log/messages
tail -f /var/log/messages Watch the file continuously, while it's being updated
tail -200 /var/log/messages Print the last 200 lines of the file to the screen
head Similar to tail, but only reads the top of the file
head /var/log/messages See the first 20 (by default) lines of /var/log/messages
head -200 /var/log/messages Print the first 200 lines of the file to the screen
more Llike cat, but opens the file one screen at a time rather than all at once
more /etc/userdomains Browse through the userdomains file. hit Spaceto go to the next page, q to quit
less Page through files
od View binary files and data
xxd Also view binary files and data
gv View Postscript/PDF files
xdvi View TeX DVI files
nl Number lines
touch Create an empty file
touch /home/burst/public_html/404.html Create an empty file called 404.html in the directory /home/burst/public_html/
file Attempts to guess what type of file a file is by looking at it's content.
file * Prints out a list of all files/directories in a directory
cp Copy a file
cp filename filename.bak Copies filename to filename.bak
cp -a /etc/* /root/etc/ Copies all files, retaining permissions form one directory to another.
cp -av * ../newdirectory Copies all files and directories recurrsively in the current directory INTO newdirectory
mv Move a file command
mv oldfilename newfilename Move a file or directory from oldfilename to newfilename
rm delete a file
rm filename.txt deletes filename.txt, will more than likely ask if you really want to delete it
rm -f filename.txt deletes filename.txt, will not ask for confirmation before deleting.
rm -rf tmp/ recursively deletes the directory tmp, and all files in it, including subdirectories.
chmod

changes file access permissions. The set of 3 go in this order from left to right:
USER - GROUP - EVERONE

0 = --- No permission
1 = --X Execute only
2 = -W- Write only
3 = -WX Write and execute
4 = R-- Read only
5 = R-X Read and execute
6 = RW- Read and write
7 = RWX Read, write and execute

chmod 000 No one can access
chmod 644 Usually for HTML pages
chmod 755 Usually for CGI scripts
chown Changes file ownership permissions
The set of 2 go in this order from left to right:
USER - GROUP
chown root myfile.txt Changes the owner of the file to root
chown root.root myfile.txt Changes the owner and group of the file to root
stat Display file attributes
grep Llooks for patterns in files
grep root /etc/passwd Shows all matches of root in /etc/passwd
grep -v root /etc/passwd Shows all lines that do not match root
ln Create's "links" between files and directories
ln -s /usr/local/apache/conf/httpd.conf /etc/httpd.conf Now you can edit /etc/httpd.conf rather than the original. changes will affect the orginal, however you can delete the link and it will not delete the original.
wc Word count
wc -l filename.txt Tells how many lines are in filename.txt
find Utility to find files and directories on your server.
find / -name "filename" Find the file called "filename" on your filesystem starting the search from the root directory "/".
locate filename Find the file name and path of which contains the string "filename". Run 'updatedb' to build index.
EDITORS Most popular editors available on UNIX platforms.
pico Friendly, easy to use file editor
pico /home/burst/public_html/index.html Edit the index page for the user's website.
vi Popular editor, tons of features, harder to use at first than pico
vi filename.txt

Edit filename.txt. All commands in vi are preceded by pressing the escape key. Each time a different command is to be entered, the escape key needs to be used. Except where indicated, vi is case sensitive. Fore more commands go to: http://www.intellink.net/vi-qref.htm

H --- Upper left corner (home)
M --- Middle line
L --- Lower left corner
h --- Back a character
j --- Down a line
k --- Up a line
^ --- Beginning of line
$ --- End of line
l --- Forward a character
w --- Forward one word
b --- Back one word
fc --- Find c
; --- Repeat find (find next c)

:q! --- This force quits the file without saving and exits vi
:w --- This writes the file to disk, saves it
:wq --- This saves the file to disk and exists vi
:LINENUMBER : EG :25 --- Takes you to line 25 within the file
:$ --- Takes you to the last line of the file
:0 --- Takes you to the first line of the file

emacs

Another popular editor. For more commands go to http://www.hsrl.rutgers.edu/ug/emacs_qref.html

C-\ t --- Tutorial suggested for new emacs users.
C-x C-c exit emacs

emacs filename.txt

Edit filename.txt. While you're in emacs, use the following quickies to get around:

C-x C-f --- read a file into emacs
C-x C-s --- save a file back to disk
C-x i --- insert contents of another file into this buffer
C-x C-v --- replace this file with the contents of file you want
C-x C-w --- write buffer to specified file

C-f --- move forward one character
C-b --- move backward one character
C-n --- move to next line
C-p --- move to previous line
C-a --- move to beginning of line
C-e --- move to end of line
M-f --- move forward one word
M-b --- move backword one word
C-v --- move forward one screen
M-v --- move backward one screen
M-< --- go to beginning of file M-> --- go to end of file





NETWORK Some of the basic networking utilities.
w Shows who is currently logged in and where they are logged in from.
who This also shows who is on the server in an shell.
netstat Shows all current network connections.
netstat -an Shows all connections to the server, the source and destination ips and ports.
netstat -rn Shows routing table for all ips bound to the server.
netstat -an |grep :80 |wc -l Show how many active connections there are to apache (httpd runs on port 80)
top

Shows live system processes in a formatted table, memory information, uptime and other useful info.

While in top, Shift + M to sort by memory usage or Shift + P to sort by CPU usage

top -u root Show processes running by user root only.
route -n Shows routing table for all ips bound to the server.
nslookup yahoo.com Query your default domain name server (DNS) for an Internet name (or IP number) host_to_find.
traceroute yahoo.com Have a look how you messages travel to yahoo.com
ifconfig Display info on the network interfaces.
ifconfig -a Display into on all network interfaces on server, active or inactive..
ping Sends test packets to a specified server to check if it is responding properly
tcpdump Print all the network traffic going through the network.
arp Command mostly used for checking existing Ethernet connectivity and IP address
SYSTEM TOOLS Many of the basic system utilities used to get things done.
ps ps is short for process status, which is similar to the top command. It's used to show currently running processes and their PID.
A process ID is a unique number that identifies a process, with that you can kill or terminate a running program on your server (see kill command).
ps U username Shows processes for a certain user
ps aux Shows all system processes
ps aux --forest Shows all system processes like the above but organizes in a hierarchy that's very useful!
kill terminate a system process
kill -9 PID Immediately kill process ID
killall program_name Kill program(s) by name. For example to kill instances of httpd, do 'killall httpd'
du Shows disk usage.
du -sh Shows a summary of total disk space used in the current directory, including subdirectories.
du / -bh | more Print detailed disk usage for each subdirectory starting at the "/".
last Shows who logged in and when
last -20 Shows only the last 20 logins
last -20 -a Shows last 20 logins, with the hostname in the last field
pwd Print working directory, i.e., display the name of my current directory on the screen.
hostname Print the name of the local host. Use netconf (as root) to change the name of the machine.
whoami Print my login name.
date Print or change the operating system date and time
time Determine the amount of time that it takes for a process to complete + other info.
uptime Show the number days server has been up including system load averages.
uname -a Displays info on about your server such as kernel version.
free Memory info (in kilobytes).
lsmod Show the kernel modules currently loaded. Run as root.
dmesg | less Print kernel messages.
man topic Display the contents of the system manual pages (help) on the topic. Do 'man netstat' to find all details of netstat command including options and examples.
reboot / halt Halt or reboot the machine.
mount Mount local drive or remote file system.
mount -t auto /dev/fd0 /mnt/floppy Mount the floppy. The directory /mnt/floppy must exist.
mount -t auto /dev/cdrom /mnt/cdrom Mount the CD. The directory /mnt/cdrom must exist.
sudo The super-user do command that allows you to run specific commands that require root access.
fsck Check a disk for errors
COMPRESSION UTILITIES There are many other compression utilities but these are the default and most widely utilized.
tar Creating and Extracting .tar.gz and .tar files
tar -zxvf file.tar.gz Extracts the file
tar -xvf file.tar Extracts the file
tar -cf archive.tar contents/ Takes everything from contents/ and puts it into archive.tar
gzip -d filename.gz gzip -d filename.gz
zip Compress files into.zip
unzip file.zip Extracting .zip files shell command
compress Compress files. compress filename
uncompress Uncompress compressed files. uncompress filename.Z
bzip2 Compress files in bzip2 format
THE (DOT) FILES The good old dot files. Let's clear up some confusion here by defining each.
.bash_login Treated by bash like .bash_profileif that doesn't exist.
.bash_logout Sourced by bash login shells at exit.
.bash_profile Sourced by bash login shells after /etc/profile
.bash_history The list of commands executed previously.
.profile Treated by bash like ~/.bash_profile if that and .bash_login don't exist.
.vimrc Default "Vim" configuration file.
.emacs Read by emacs at startup
CONFIGURATION FILES Listing everything is beyond the scope of this article.
/etc This directory contains most of the basic Linux system-configuration Files.
/etc/init.d Contains the permanent copies of System V–style run-level scripts. These scripts are often linked to files in the /etc/rc?.d directories to have each service associated with a script started or stopped for the particular run level. The ? is replaced by the run-level number (0 through 6). (Slackware puts its run-level scripts in the /etc/rc.d directory.)
/etc/cron* Directories in this set contain files that define how the crond utility runs applications on a daily (cron.daily), hourly (cron.hourly), monthly (cron.monthly), or weekly (cron.weekly) schedule.
/etc/cups Contains files used to configure the CUPS printing service.
/etc/default Contains files that set default values for various utilities. For example, the file for the useradd command defines the default group number, home directory, password expiration date, shell, and skeleton directory
/etc/skel Any files contained in this directory are automatically copied to a user’s home directory when that user is added to the system.
/etc/mail Contains files used to configure your sendmail mail service.
/etc/security Contains files that set a variety of default security conditions for your computer.
/etc/sysconfig Contains important system configuration files that are created and maintained by various services (including iptables, samba, and most networking services).
/etc/passwd Holds some user account info including passwords (when not "shadowed").
/etc/shadow Contains the encrypted password information for users' accounts and optionally the password aging information.
/etc/xinetd.d Contains a set of files, each of which defines a network service that the xinetd daemon listens for on a particular port.
/etc/syslogd.conf The configuration file for the syslogd daemon. syslogd is the daemon that takes care of logging (writing to disk) messages coming from other programs to the system.
/var Contains variable data like system logging files, mail and printer spool directories, and transient and temporary files.
/var/log Log files from the system and various programs/services, especially login (/var/log/wtmp, which logs all logins and logouts into the system) and syslog (/var/log/messages, where all kernel and system program message are usually stored).
/var/log/messages System logs. The first place you should look at if your system is in trouble.
/var/log/utmp Active user sessions. This is a data file and as such it can not be viewed normally.
/var/log/wtmp Log of all users who have logged into and out of the system. The last command can be used to access a human readable form of this file.
Apache Shell Commands Some of the basic and helpful apache commands.
httpd -v Outputs the build date and version of the Apache server.
httpd -l Lists compiled in Apache modules
httpd status Only works if mod_status is enabled and shows a page of active connections
service httpd restart Restarted Apache web server
MySQL Shell Commands Some of the basic and helpful MySQL commands.
mysqladmin processlist Shows active mysql connections and queries
mysqladmin processlist |wc -l Show how many current open connections there are to mysql
mysqladmin drop database Drops/deletes the selected database
mysqladmin create database Creates a mysql database
mysql -u username -p password databasename <> Restores a MySQL database from data.sql
mysqldump -u username -p password database > data.sql Backup MySQL database to data.sql
echo "show databases" | mysql -u root -p password|grep -v Database Show all databases in MySQL server.
mysqldump -u root -p password database > /tmp/database.exp Dump database including all data and structure into /tmp/database.exp

Getting ur point accross

Have you ever found yourself saying, "Well, I was just being honest"? This is a classic communication issue: The speaker and listener have drastically different perceptions about the meaning of a message. This effect is amplified when you think you're being authentic (or honest, or transparent, or up front). Without knowing your intention, or if you lack the interpersonal skill to frame an authentic message well, the listener may think you' re rude and no longer wish to continue any sort of relationship with you, much less a productive conversation.

In a business setting, a higher degree of professionalism might be standard. So being authentic requires a balance between being forthright and gaining the interpersonal skill that allows you to be more sensitive and diplomatic

While we can' t cover every possible interaction here, we will share key points as you look to polish your interpersonal skill and, at the same time, become more authentic in your communications. Notice the "raw comments" versus "polished comments" for each of the examples below.

Five tips for skillful authenticity

1. Get more information before making a statement. Making a statement rather than asking a question closes off the possibility that you' ll gain additional understanding and increases the likelihood that you'll be perceived negatively. Don' t jump to the conclusion that your way's the only way without getting the full story.

Raw: That's never going to work.
2. Polished: I don't have enough information yet to get behind this and see how it will help improve project outcomes. Can you tell me more about what you' re proposing?
3. Check out any assumptions you might be making. If you think you've made an assumption, ask (and if you don't think you make any assumptions, you've just made a big one!). More often than not, because of our own filters, what we hear is quite different from what someone has actually said and certainly different from what they might have intended to say. Get clarity as quickly as possible to avoid tainting the interaction with a misconception made early on.

Raw:You're trying to keep me out of the loop, and you're talking down to me.

Polished: I'm making the assumption that you think I shouldn't be involved in this project and that you think I'm less qualified on this subject than you are. Is that correct?

Raw: You need to do a great job on this project, or we'll all be in trouble.

Polished: In order to fulfill expectations for success on this project, you need to improve our customer relations feedback from fair to good within six months of starting the new approach. Knowing that, is there anything else we need to add to help meet that goal?
4. Keep everyone focused on the goal and intention. Create common ground on which to share your perspective. This helps people maintain understanding without hitting hot buttons as quickly or ferociously.

Raw: I don't work that way, I have high standards.

Polished: I have some concerns about doing it this way, particularly that our approach will seem rude to customers. I'd like to propose another option that leads to the same goals.
5. Know the difference between inquiry and advocacy. Much of the time, conversations go nowhere or aren't as productive as they could be, because participants are too busy trying to convince others that their position is the correct one. Spend time inquiring into another participant's position, as well as sharing why you've arrived at your own position. Remember, your truth isn't the only truth, and you may not even be right. Keeping this in mind helps us be more humble as we enter into conversation with others.

Raw: We can't do that. We have to do what I've suggested, or the project won't work.

Polished: Tell me more about how your suggestion might help us reach our goal for this project, and then I'd like to share more information about my own suggestion.
6. Set the stage. Demonstrate your authenticity by telling people that you might not have it down pat yet. This comment instantly brings your audience to the table in terms of how you're operating and what they might expect. Note: Don't use this rule as an excuse to shoot off your mouth about anything. Use it as a guide to your intentions.

Raw: I'm going to say what I'm feeling and thinking.

Polished: Before we get started, I want to let you know that I'm trying to be more authentic. Do all of you feel comfortable with this? (Offer to share examples of your candor.)

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Hate Love letter

Read this "HATE letter". It is so funny and creative.
This is a loveletter from a boy to a girl.... However, the girl's
father does not like him and want them stop their relationship......and so..
the boy wrote this letter to the girl..he knows that the girl's father
will definitely read this letter..
1 "The great love that I have for you
2 is gone, and I find my dislike for you
3 grows every day. When I see you,
4 I do not even like your face;
5 the one thing that I want to do is to
6 look at other girls. I never wanted to
7 marry you. Our last conversation
8 was very boring and has not
9 made me look forward to seeing you again.
10 You think only of yourself.
11 If we were married, I know that I would find
12 life very difficult, and I would have no
13 pleasure in living with you. I have a heart
14 to give, but it is not something that
15 I want to give to you. No one is more
16 foolish and selfish than you, and you are not
17 able to care for me and help me.
18 I sincerely want you to understand that
19 I speak the truth. You will do me a favor
20 if you think this is the end. Do not try
21 to answer this. Your letters are full of
22 things that do not interest me. You have no
23 true love for me. Good-bye! Believe me,
24 I do not care for you. Please do not think that
25 I am still your boyfriend."
So bad!! However, before handing over the letter to
the girl, the boy told the girl to "READ BETWEEN THE
LINES", meaning-only to read
1.3.5.7.9.11.13.15.17.19.21.23.25. (Odd
Numbers) So..Please try reading it again! It's so
smart & sweet....

If Guru Dutt had been a software consultant in the US

(The following should be sung to the tune of an old Hindi classic song
sung by late Mohammed Rafi. "Yeh Duniya agar mil bhi jayaye to kya
hai...")


Yeh Document, Yeh Meetings, Yeh Features Ki Duniya
Yeh Insaan Ke Dushamn, Cursors Ki Duniya
Yeh Deadlines Ke Bhooke, Management Ki Duniya
Yeh Product Agar Ban Bhi Jaaye To Kya Hain?

Yahaan Ek Khilona Hain Programmer Ki Hasti
Yeh Basti Hain Murda Bug-Fixers Ki Basti
Yahaan Par Toh Raises Hain, Iinflation Se Sasti

Yeh Review Agar Ho Bhi Jaaye Toh Kya Hain?
Har Ek Keyboard Ghayal, Har Ek Login Pyaasi
Excel Mey Uljhan, Winword Mey Udaasi

Yeh Office Hain Ya Aalame Microsoft Ki
Yeh Release Agar Ho Bhi Jaaye To Kya Hain?

Jalaa Do Isey, Phoonk Do Yeh Monitor
Mere Saamne Se Hataa Do Yeh Modem
Tumhara Hain Tumhi Sambhaalo Yeh Computer
Yeh Product Agar Chal Bhi Jaaye Toh Kya Hain?

Sociable

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