Tech Kaki » Fedora

Linux – Use the Terminal to Display a Calendar

@HKw@! — Tue, 13 Jul 2010 15:44:25 +0000

In Linux environment, we can view the calendar directly in the terminal. To do this, just simply use the “cal” command

cal command is used to display the calendar. Below are the syntax:-

cal [options] [month{1-12}] [year{1-9999}]

OPTIONS:

-1	Displays single month as output.
-3	Displays prev/current/next month output.
-s	Displays sunday as the first day of the week.
-m	Displays Monday as the first day of the week.
-j	Displays Julian dates (days one-based, numbered from January 1).
-y	Displays a calendar for the current year.

Example:

To use this command, open a Terminal window and type the cal command:

By default, the command displays a calendar for the current month.

To display calendar for year 2010

To display calendar of the month Feburary 2010

If you wish to learn more how to use cal command, just type ‘man cal‘ for more details

cal COMMAND:
cal command is used to display the calendar.

SYNTAX:
The Syntax is
cal [options] [month] [year]

OPTIONS:

-1	Displays single month as output.
-3	Displays prev/current/next month output.
-s	Displays sunday as the first day of the week.
-m	Displays Monday as the first day of the week.
-j	Displays Julian dates (days one-based, numbered from January 1).
-y	Displays a calendar for the current year.

Forgotten root Password

@HKw@! — Fri, 02 Jul 2010 10:22:39 +0000

I forgot my Red Hat Server root password. What i need to do to recover the root password?

In RedHat Linux, we can recover the root password by log in single-user mode and create a new root password.

Below are the steps:-

Power on, or reboot your RedHat Machines
At the boot loader menu, use the arrow keys to highlight the installation you want to edit and type [A] to enter into append mode.

After that, you should see the screen similar to the following

grub append> ro root=/dev/VolGroup00/LogVol00 rhgb quiet

Press the Spacebar once to add a blank space, then add the word single and press Enter to tell GRUB to boot into single-user Linux mode.

grub append> ro root=/dev/VolGroup00/LogVol00 rhgb quiet single

After it finishes loading, you will get a shell prompt

sh-3.2#

Now you can change the root password by enter the following command

sh-3.2# passwd root

After that, reboot your machine

sh-3.2# reboot

Now you should able to log in to root with your new changed password.

How to list out Hidden Files and Folder in linux

@HKw@! — Wed, 09 Jun 2010 13:22:04 +0000

In Windows XP/Vista/7, we can easily view the hidden files or folder by check the “view hidden file” option. How about linux? Linux do not have “view hidden file” option, any idea?

Here are the quick tip:-

a) Use command

open the terminal, type the following command to list the hidden files and folder

# ls -a

or

# ls -la

B) Use shortcut key
If you use linux with interface, try to press Ctr + H . It will show the hidden files and directory folders start with a period (.) . I tried this commnad on Gnome interface linux, it work fine. I think it should working find in KDE interface.

Enjoy.

Fedora/Centos: How to Mount and Unmount ISO Files

@HKw@! — Mon, 07 Jun 2010 13:15:12 +0000

An ISO image or .iso file contains the disk image of an ISO 9660 file system. According to WIKIPEDIA, ISO 9660, also referred to as CDFS (Compact Disc File System) by some hardware and software providers, is a file system standard published by the International Organization for Standardization (ISO) for optical disc media (CD-ROMs and DVD-ROMs).

In Linux, it is possible to mount the ISO image so that you can access the files without having to actually burn it to disk. Here is the simple way to show you mount and unmount ISO images without burning them.
1) You must login as a root user

$ su -

2) create a mount point

# mkdir /mnt/iso

3) To mount the ISO image file.iso to the mount point /mnt/iso, run the follwing command:-

# mount -o loop -t iso9660 /home/techkaki/file.iso /mnt/iso

or

# mount -o loop /home/techkaki/file.iso /mnt/iso

If you not specifying the “-t iso9660″ , it will work. The mount command is smart enough to work out that it’s a CD image.

4) Now you can verify that the ISO image is mounted

# ls -l /mnt/iso

or

# df -hT
Filesystem    Type    Size Used Avail Use% Mounted on
/dev/mapper/vg_techkaki-lv_root
ext4     72G   24G   48G 33% /
tmpfs        tmpfs    976M 6.3M 969M   1% /dev/shm
/dev/sdb1     ext4    194M   94M   90M 52% /boot
/dev/sdc1 fuseblk     21G   16G 4.9G 76% /media/5ECCB927CCB8FA7B
/dev/sdc5 fuseblk     55G   46G 9.5G 83% /media/data
/dev/loop0 iso9660    7.4G 7.4G     0 100% /mnt/iso

To unmount the ISO Image, use following command :

# umount /mnt/iso

How to open .chm file in Linux

@HKw@! — Thu, 08 Apr 2010 06:47:22 +0000

I downloaded an ebook from internet. The ebook in .chm extension. I can’t read it in my linux machine.

So, i just install a software called xCHM to read .chm file. xCHM can show the content tree if one is available, print pages, change font face and size, remember bookmarks, display a searchable index, and search for words in the current page and the whole book.

How to install it? Just follow the following steps:-

Fedora/Centos

a) Login as root user

su -

b) Type the following command to install it

yum install -y xchm

After that, you try to double click the .chm file, you should able to open it with xchm program.

How to find your MAC address (Linux/Windows/Mac OS X)

@HKw@! — Thu, 18 Mar 2010 14:44:54 +0000

Windows XP/Vista/7
Run ipconfig/all from a Command Prompt window.

click Start, then Run, then type cmd in the text box.

Type in ipconfig/all in the Command Prompt Windows and press enter

You should get something like this

Your MAC Address is listed under ‘Physical Address’ as a series of 6 groups of two digits, letters and numbers, separated by dashes, such as in the image below. Make sure you get the physical address of the correct network adapter – usually there are several listed.

Linux

On Linux systems, you must login as root user first before you find the Mac Address

Launch your terminal
Type the following command to become root user

[ahkwai@techkaki ~]$ su -
Password:

Then, type ifconfig. Example:-

MAC OS X

Choose “System Preferences...” from the Apple menu. Then select “Network.” Double-click on “Airport” or “Built-in Ethernet” depending on how you access the Internet or your network.

For ‘Built-in Ethernet’, select the Ethernet tab. Read the MAC address labeled ‘Ethernet ID:’.

Basic Linux Commands

@HKw@! — Wed, 17 Feb 2010 04:29:42 +0000

Viewing, copying, moving and deleting files

ls	Display the contents of the current directory
ls -a	Display also hidden files and hidden directories

cp filename /path/dir_name	Copy filename into directory /path/dir_name
cp -r dir_name /path/dir_name2	Copy the entire dir_name into /path/dir_name2
cp filename1 filename2 /path/dir_name	Copy filename1 and filename2 into /path/dir_name

rm name	Remove a file or directory called name
rm -r name	Remove an entire directory as well as its included files and subdirectories

mv filename /path/dir_name	Move filename into /path/dir_name
mv filename1 filename2	Rename filename1 to filename2

cat filename	Display filenames contents

more filename	Display filename in pages. Use spacebar to view next page

head filename	Display filenames first 10 lines
head -15 filename	Display filenames first 15 lines

tail filename	Display filenames last 10 lines
tail -15 filename	Display filenames last 15 lines

pwd	Display current directory

cd /path/dir_name	Change to directory /path/dir_name
cd ..	Go 1 directory up

mkdir dir_name	Create directory dir_name
rmdir dir_name	Delete directory dir_name

Finding files and text within files

updatedb	Update (create first time used) a database of all files under the root directory /
locate filename	Find file filename searching in the database

find / -name filename	Starting from the root directory search for the file called filename
find / -name *filename	Same as above but search for file containing the string filename

grep string /path/dir_name	Starting from /path/dir_name search for all files containing string

which application_name	Search $path for application app_name
whereis application_name	Search $path, man pages and source files for application_name

Archived files

Decompress

tar -xzf filename.tgz	Decompress tzg file
tar -xzf filename.tar.gz	Decompress tar.gz file
tar -xjf filename.tar.bz2	Decompress tar.bz2 file

Compress

tar -czf filename.tar /path/dir_name	Compress directory /path/dir_name to filename.tar
gzip -c filename > filename.gz	Compress /path/dir_name to filename.tar.gz
bzip2 -c filename > filename.bz2	Compress /path/dir_name to filename.tar.bz2

Using rpm files

rpm -hiv package.rpm	Install rpm called package.rpm
rpm -hiv –force package.rpm	Install rpm called package.rpm by force
rpm -hUv package.rpm	Upgrade rpm called package.rpm
rpm -e package.rpm	Delete rpm called package.rpm
rpm -qpil package.rpm	List files in not-installed rpm called package.rpm
rpm -ql package.rpm	List files in installed rpm called package.rpm
rpm -q str	List installed rpms containing the string str
rpm -qf /path/application_name	Display the rpm that contains application application_name

Starting and Stoping

startx	Start the X system
shutdown -h now	Shutdown the system now and do not reboot
halt	Same as above
shutdown -r now	Reboot
reboot	Same as above
shutdown -r +10	Reboot in 10 minutes

Mounting filesystems

mount -t vfat /dev/sd(a)(1) /mnt/c_drive	Mount the first partition 1 of the first hard disk drive a which is in fat32 vfat dormat under /mnt/c_drive directory
mount -t iso9660 /dev/cdrom /mnt/cdrom	Mount cdrom under /mnt/cdrom directory

umount /mnt/hda1	Unmout the above

User administration

users	Display users currently logged in
adduser username	Create a new user called username
passwd username	Define password for user called username
who	List logged-in users
whoami	Display current user
finger username	Displays info about user username
su	Log in as root from current login
su -	Log in as root from current login and take root’s path
exit	Exit from console login (ie, logout).

Processes

command	Execute command in the foreground
command &	Execute command in the background
ctrl+z	Suspend a program
ctrl+c	Interrupt a program
ps	List all processes
kill -9 pid	Kill process with id pid
top	Monitor processes in real time

Networking

hostname	List the system’s hostname
ifconfig	Set/Display network information
host ip	Resolves ip’s hostname
ping ip/hostname	Check if ip/hostname is reachable
traceroute ip/hostname	Find network path to ip/hostname

System Information

uname -a	General system information
fdisk -l	List partition tables
cp filename /path/dir_name	Copy filename into directory /path/dir_name
df -T -h	List filesystem disk space usage
lspci	List PCI devices
lsusb	List USB devices
free -m	Display RAM+Swap usage

Program Compile

gcc -o output file.c	Compile a C program
./output	Run a C program you have compiled
g++ -o output file.cpp	Compile a C++ program
./output	Run a C++ program you have compiled
./configure && make && su -c ‘make install’	Configure, compile and install a program with Makefile

How to open winrar files on Linux (Fedora/Ubuntu)

@HKw@! — Mon, 04 Jan 2010 09:35:57 +0000

I just downloaded .rar file. But i can’t open it under my Fedora operating systems. How to open it?

RAR is a proprietary compression format widely used today. By default, Fedora unable to open RAR files. So, you need to install a software called unrar.

How to install unrar on Fedora?

Just use yum command as follows :

# yum install unrar

Under Ubuntu, you need to type apt-get as follows to install unrar program:

# apt-get install unrar

How to use unrar?

Extract a RAR file into the current directory.

# unrar e [filename].rar

eg: # unrar e testing.rar

List contents of a RAR file

# unrar l [filename].rar

eg: # unrar l techkaki.rar

If you want to know more on how to use unrar function, you just type man unrar on your terminal.

How to Configure Mac OS X to access your NTP Server

@HKw@! — Wed, 16 Dec 2009 11:11:29 +0000

Once you finished setup your NTP server, you need to allow your NTP client to access the NTP Server. Here i going to show your how to configure your NTP Client (Mac OS X) to sync the time from your NTP Server. Below are the steps:

1st – Launch your terminal

2nd – From the terminal, type the following command

techkaki-MacBook:~ techkaki $ sudo vi /etc/ntp.conf

3rd – change the default timezone address to your server domain name or ip address

By default, it will point to apple timezone. Eg: server time.asia.apple.com

To change it, just change the URL to your server ip or server domain name

eg: server 192.168.1.2 or server ntp.techkaki.com

4th – Save the ntp.conf

Now you will realize that your Mac timezone already point to your ntp server.

How to change ntp timezones on NTP Server (centos/fedora/RedHat)

@HKw@! — Wed, 16 Dec 2009 10:53:05 +0000

After you setup the NTP server. You will realize that the timezone was changed. The time zone might not same as your country timezone. It is because pool.ntp.org will assign the timeservers from all over the world, time quality will not be ideal.

You will get better result if you use the continental zones. Just click Here to view the available zone in All Pool serves.

Here i will going to show how to change the timezone on your NTP Server.

1st – Login as the root user

2nd – Now open and edit /etc/ntp.conf

# vi /etc/ntp.conf

3nd – Now i want to add Malaysia timezone to NTP server. Just add the following to your ntp.conf file:

	   server 0.my.pool.ntp.org
	   server 1.asia.pool.ntp.org
	   server 2.asia.pool.ntp.org

4th – Save the ntp.conf file and restart the ntpd service

# service ntpd start

Now you will realize that your timezone was change