Configuring Yum in RHEL5

Configuring Yum in RHEL5

In this article I am going to discuss how we can configure Yum for DVD sources in RHEL5.
Yum is the package management tool used these days. It has replaced the old "up2date" command which use to come with RHEL4. This command used to get updates from the RHN (Redhat Network) for the installed operating system, if the user using that command had bought a support/update entitlement from Redhat. But with the new version of Redhat and then it's free clone Centos5 "up2date" has been dropped out and instead of it "yum" as been included. "yum" was there in Fedora core for a long time and was use to update packages via 3rd party repositories. It started becoming mature with Fedora and now finally when Redhat thought it to be matured enough to make it's way into RHEL it's here.

The major problem one face with Yum is to configure it for DVD/CD sources. Yum by default doesn't comes enabled for these sources and we need to explicitly enable it. I don't know what is the reason behind not enabling Yum for these sources by default but, whatever it is we can still hack "yum" on our own and can configure it to use DVD/CD install sources.

Before starting I would like to mention that I am using a DVD source in this article which is represented by "/dev/dvd" and mounted on "/media/cdrom". The steps I tell here can be easily extended for CD sources as well. Later in this article I will tell how we can configure a local yum repository and use it for package management in our LAN clients.

First of all you have to put in the media CD/DVD into your CD/DVD ROM/Writer. Then you need to mount it manually if you are login via root user in a GUI. To do so

mount /dev/dvd /media/cdrom

After mounting the DVD we need to copy the content of the DVD onto a directory. For example I have a directory /dvd/rhel5/. I will copy the whole contents of /media/cdrom into /rhel5. This is the command

cp -r /media/cdrom/* /dvd/rhel5/

After copying the contents it's time to do some modifications. First of all we need to bring the xml files defining the groups to directory one level higher.

mv /dvd/rhel5/Server/repodata/comps-rhel5-server-core.xml /dvd/rhel5/Server
mv /dvd/rhel5/VT/repodata/comps-rhel5-vt.xml /dvd/rhel5/VT
mv /dvd/rhel5/Cluster/repodata/comps-rhel5-cluster.xml /dvd/rhel5/Cluster
mv /dvd/rhel5/ClusterStorage/repodata/comps-rhel5-cluster.xml /dvd/rhel5/ClusterStorage

Now we need to delete the repodata/ directories which comes with the default install tree. The reason behind this is that in their xml files we have a string
xml:base="media://1170972069.396645#1" .....
This string is present in repmod.xml as well as primary.xml.gz. This thing creates problem with using DVD/CD sources with yum. So we need to do the following

rm -rf /dvd/rhel5/Server/repodata
rm -rf /dvd/rhel5/VT/repodata
rm -rf /dvd/rhel5/Cluster/repodata
rm -rf /dvd/rhel5/ClusterStorage/repodata

After we have deleted the default repodata/ directories it's time to re-create them using the "createrepo" command. Now this command doesn't comes by default I guess so we need to install it's rpm

rpm -ivh /dvd/rhel5/Server/createrepo-0.4.4-2.fc6.noarch.rpm

Next step is to run this command. Before running this command we need to switch to the /dvd/ directory. Then run the commands listed below

createrepo -g comps-rhel5-server-core.xml dvd/Server/
createrepo -g comps-rhel5-vt.xml dvd/VT/
createrepo -g comps-rhel5-cluster.xml dvd/Cluster/
createrepo -g comps-rhel5-cluster-st.xml dvd/ClusterStorage/

The above commands will do most part of the job. Now it's time to configure the /etc/yum.conf for our local repository. Note that we can also create separate repo files in /etc/yum.repos.d/ directory but I have tried it without any luck. So do the following

vi /etc/yum.conf

In this file type in the following: # PUT YOUR REPOS HERE OR IN separate files named file.repo

# in /etc/yum.repos.d
[Server]
name=Server
baseurl=file:///dvd/rhel5/Server/
enabled=1
[VT]
name=Virtualization
baseurl=file:///dvd/rhel5/VT/
enabled=1
[Cluster]
name=Cluster
baseurl=file:///dvd/rhel5/Cluster/
enabled=1
[ClusterStorage]
name=Cluster Storage
baseurl=file:///dvd/rhel5/ClusterStorage/
enabled=1

We can also use GPG key signing. For that write on top of the above lines

gpgenabled=1
gpgkey=file:///dvd/rhel5/RPM-GPG-KEY-fedora file:///dvd/rhel5/RPM-GPG-KEY-fedora-test file:///dvd/rhel5/RPM-GPG-KEY-redhat-auxiliary file:///dvd/rhel5/RPM-GPG-KEY-redhat-beta file:///dvd/rhel5/RPM-GPG-KEY-redhat-former file:///dvd/rhel5/RPM-GPG-KEY-redhat-release

This will be sufficient for now. Let's create the yum cache now.

yum clean all
yum update

It's all done now. We can now use "yum" command to install/remove/query packages and now yum will be using the local yum repository. Well I am mentioning some of the basic "yum" commands which will do the job for you for more options to the "yum" command see the man page of "yum".
yum install package_name Description: Installs the given package
yum list Description: List's all available package in the yum database
yum search package_name Description: Search for a particular package in the database and if found print's a brief info about it.
yum remove package_name Description: Remove's a package.

Now I will mention the steps you can use to extend this local repository to become a local http based repository so that LAN clients can use it for package management. I will be using Apache to configure this repository as it's the best available software for this job. Do configure the repository for http access via LAN clients we need to make it available to them. For that I am declaring a virtualhost entry in apache's configuration file. This is how it looks for me


ServerAdmin webmaster@server.example.com
ServerName server.example.com
DocumentRoot "/dvd/rhel5/"
ErrorLog logs/server.example.com-error_log
CustomLog logs/server.example.com-access_log common


After this service httpd start
chkconfig httpd on

Now it's time to make a yum.conf file that we will use at the client end. I am writing my yum.conf for clients. You can use it and modify according to your setup.

[main]
cachedir=/var/cache/yum
keepcache=0
debuglevel=2
logfile=/var/log/yum.log
pkgpolicy=newest
distroverpkg=redhat-release
tolerant=1
exactarch=1
obsoletes=1
plugins=1
metadata_expire=1800
gpgcheck=1

# PUT YOUR REPOS HERE OR IN separate files named file.repo
# in /etc/yum.repos.d
[Server]
name=Server
baseurl=http://192.168.1.5/Server/
enabled=1
[VT]
name=Virtualization
baseurl=http://192.168.1.5/VT/
enabled=1
[Cluster]
name=Cluster
baseurl=http://192.168.1.5/Cluster/
enabled=1
[ClusterStorage]
name=Cluster Storage
baseurl=http://192.168.1.5/ClusterStorage/
enabled=1

Copy this file to /etc/ directory of the client end and replace it with the original file there. After copying is done it's time to do this

yum clean all
yum update
rpm --import /etc/pki/rpm-gpg/*

Now you can use yum on the client end to just install any package and it will communicate with the local repo server to get the package for you. You can also use pirut in the same way to get things done.

So this is how we can configure Yum for RHEL5 Server and can also use it to create our own local repo server for the LAN. Hope you have enjoyed reading and had your hands done on this :).

Run Windows applications on Linux with WINE

One of the biggest reasons why some organizations resist the move to Linux is the lack of applications available for Linux users—or, more specifically, the lack of Windows applications. However, just because you want to run Linux as your operating system, that doesn't mean you have to abandon your favorite Windows application. You might be able to get it to run on Linux using WINE.

What's WINE?
WINE is an ongoing project that is intended to allow Linux users to run Windows applications in a Linux environment. Although not all Windows applications will run under WINE, WINE is undergoing constant changes and many Windows applications can now be made to run under WINE.

Why WINE?
Although there are quite a few Windows applications that just don’t work with WINE and other Windows applications that install on WINE but crash frequently, there are still several reasons for using WINE. The biggest reason is to get away from Windows. Let’s face it, it’s easy to get an office suite for Linux, but most companies are unable to completely make the transition to Linux from Windows because they have a couple of mission-critical applications that simply do not run under Linux.

Companies might want to move from Windows to Linux for a number of reasons. For starters, there have been rumors that Microsoft has been considering adopting a software license model, which requires you to lease all of your Microsoft software on an ongoing basis. Many companies simply could not afford to do this. Running Linux and WINE would release you from the Microsoft monopoly.

Another reason for making the switch is because of all of the security holes in Windows. If a hacker group managed to find a major vulnerability in Windows, it would be theoretically possible to exploit that vulnerability on 80 percent of the world’s computers. However, if you switched to Linux and ran WINE, you would not be affected by any vulnerabilities that might exist within the Windows operating system because you would not be running Microsoft code.

Please note that I’m not writing this article to debate which is the better operating system. I only want to point out that there are some valid reasons why companies that have already rolled out Linux to a limited degree may want to press forward in their transition.

OK, so there are some reasons why it might be desirable to run Windows programs on Linux, but why use WINE? Why not just use an emulator such as VMWare? The truth is that when WINE works, it outperforms VMWare. Furthermore, if you want to emulate a Windows virtual machine, VMWare requires you to purchase a copy of Windows to install within the virtual machine. While it’s true that VMWare works really well, you are actually running an operating system on top of an operating system (Windows on top of Linux). This makes for some really slow performance. By the time that you pay for a copy of VMWare and the high costs associated with running Windows, running VMWare tends to be a bit pricey too.

WINE, on the other hand, is not an emulator. WINE simply uses a WIN32 API to make Windows code run on a native Linux / X Windows system. In theory, adding an extra layer of abstraction should slow things down a little bit. However, assuming that you have decent hardware, Windows applications running under WINE should perform comparably to native Linux applications. This raises the question of what constitutes decent hardware.

Hardware requirements
WINE’s hardware requirements are minimal to say the least. The first requirement is that WINE requires an X86 processor. A common misconception is that WINE is an emulator and can, therefore, run Windows applications on other platforms, such as Solaris. This is simply not true. In fact, the name WINE is an acronym that stands for Wine Is Not an Emulator. Because WINE is not emulating an X86 processor, an actual X86 processor is required.

To be more specific, WINE requires a minimum of an 80386 processor. The 80386 processor addresses memory in a very different way from prior Intel processors, and WINE depends on these differences. Even though WINE will technically run on an old 386 machine, don’t expect to be able to dig an old 386 with a 20 MB hard driver out of the closet and run WINE on it. WINE requires a whole lot more hard disk space than the low processor requirements might lead you to expect. You will need at least 250 MB of disk space just to store and compile the WINE source code. Additionally, the installation requires about another 70 MB of disk space, 20 MB of which must be available within your TMP directory.

It seems that the jury is still out on WINE’s memory requirements. There is a lot of contradictory information on the Internet regarding WINE’s memory requirements. The one thing that all of the sites do agree on though is that WINE’s debugger is memory hungry. One Web site claimed that it is possible, but not advisable, to run WINE with 8 MB of RAM and an 8-MB swap file. Another Web site suggested that 16 MB of RAM was the minimum but that WINE was painfully slow even with 24 MB of RAM. There seems to be a general consensus, though, that WINE will do a decent job of running most supported Windows applications if the computer has at least 64 MB of RAM.

Obtaining and installing WINE
Installing and configuring WINE takes a lot of work. The first step in the process is to download the WINE binaries. You can download the binaries from the WINE HQ Web site. The installation process differs depending on your Linux distribution type.

Linux distributions from Red Hat, Mandrake, and many others require you to install the binaries through the RPM command. To do so, you would enter the following command:
RPM –I WINE-xxxxxxxx-I386.RPM

In this command, xxxxxxxx represents the version number of the WINE RPM file that you have downloaded.

If you are using a Debian-based Linux distribution, you will use a different command to install the WINE binaries. The command is:
APT-GET INSTALL WINE

Whichever technique you use, the WINE binaries will be installed in the /USR/LOCAL folder unless you specify a different location.

Configuring WINE
Before you can use WINE, you must verify that the WINE configuration file is in the correct location. Most of the time it won’t be. After the initial installation, the configuration file will exist within the /URS/SHARE/DOC/WINE-xxxxxxxx/SAMPLES folder. You must copy this file to the ~/.WINE folder. To do so, you would enter the two commands shown below. The first command creates the ~/.WINE/ folder while the other copies the configuration file.
MKDIR ~/.WINE/
CP /USR/SHARE/DOC/WINE-xxxxxxxx/SAMPLES/CONFIG ~/.WINE/CONFIG

The configuration file has a lot to do with how well or even if an application will run. The default configuration file will work fine for a lot of applications, but there are times when you may want to tweak it. Tweaking the configuration file is beyond the scope of this article, but if you would like to see how it’s done, check out the directions found at the WINE Web site.

Installing and running Windows applications
Now that WINE is installed, you are probably anxious to try running a Windows application. Unlike Linux, most Windows applications have an executable Setup program. Usually this application is named SETUP.EXE, but the name does occasionally vary.

To install a Windows application, the first thing that you have to do is to make the CD that contains the application available to Linux. You can do so by using the following two commands:
MOUNT /DEV/CDROM
CD /DEV/CDROM

Now, simply issue the WINE command followed by the name of the Windows executable that you want to run (usually SETUP.EXE). The command would look like this:
WINE SETUP.EXE

When you run SETUP.EXE, you will launch the installation wizard for the application. Just follow the various prompts to complete the installation. If Setup completes successfully, then you are ready to run your Windows application. The next section of this article explains exactly how to go about doing so. If the Setup program crashes or hangs, though, then you will have to do a little clean up work.

If you have a Setup program that has hung, then the first thing that you must do is to press [CTRL][Alt][F1] to return to the main console screen. Now, login as root and then use the following command to kill the hung process:
KILLALL -9 WINE

This should terminate any processes that are running under WINE, but the process doesn’t always work. You must verify that the WINE-related processes have indeed been terminated. You can do so by issuing the following command:
PS-AX

This will list the currently running processes. If any WINE processes are listed, then pay attention to the process ID. Now, issue the following command where yyy is the process number for the process that you need to terminate:
KILL -9 yyy

Running a Windows application
Now that I have shown you how to set up a Windows application, let’s take a look at how to run the application once it has been installed. I recommend starting out with something simple. Try running Notepad. Notepad is actually built in to WINE and you can run Notepad just by entering NOTEPAD at the command line. If Notepad runs, then it means that your configuration file is set up correctly and you can try running a more elaborate application.

Basically, running a Windows application involves switching to the Windows directory, and then calling WINE along with the application name. In the example below, I am using APDIR to represent the name of the folder where my fictitious Windows application is installed. I am also using APPLICATION.EXE to represent the application’s executable. With this in mind, you would launch your Windows application by using the following two commands:
CD /APDIR
WINE APPLICATION.EXE – APPLICATION.EXE –CONSOLE

Troubleshooting
If Notepad fails to run, then WINE hasn’t been installed or configured correctly. In order to work, WINE requires some specific directories to be present beneath the .WINE/ directory. Normally, these directories should be automatically created during the installation process, but you can check to make sure that the directories actually exist. If they don’t exist, try creating them manually. The necessary directories include:

• .wine/c_drive
• .wine/c_drive/Windows
• .wine/c_drive/Windows/Fonts
• .wine/c_drive/Windows/Start Menu/Programs
• .wine/c_drive/Windows/System
• .wine/c_drive/Windows/System32
• .wine/c_drive/Windows/Temp
• .wine/c_drive/Program Files
• .wine/c_drive/Program Files/Common Files

In case you are wondering, Linux doesn’t use drive letters (C:, D:, etc.) the way that Windows does. Windows applications expect to have access to a lettered drive. WINE treats the .WINE/C_DRIVE folder as the C: drive.

Another thing to check for is for the existence of the SYSTEM.INI and WIN.INI files within the .WINE/WINDOWS directory. Again, these files should already exist, but if they don’t, you can copy them from the WINE-xxxxxxxx/DOCUMENTATION/SAMPLES directory.

Earlier, I briefly mentioned the WINE configuration file. You shouldn’t normally have to change anything in the configuration file to get Notepad to run. If Notepad doesn’t run, though, you might check to make sure that the correct paths are specified within the configuration file. This is also a good time to make sure that the configuration file has the correct map point for the CD-ROM drive. The CD-ROM drive’s map point doesn’t really have anything to do with Notepad running or not running, but checking the map point now may save you some troubleshooting later when you try to run a real application.

Installing TrueType fonts
One of the biggest problems with using WINE to run a Windows application is that many Windows applications rely on TrueType fonts. As you may know, TrueType fonts are not natively supported by WINE. Therefore, if you have an application that is TrueType-font dependent, you’ll have to make Linux know what to do with TrueType fonts.

The easiest method for doing this is to download an X font server for TrueType fonts called XFSTT. If you need the RPM file, you can get it from this RPM resource xfstt page.

Once you download and install the TrueType font server package, you will have to copy the TrueType fonts off of a Windows machine to your Linux machine. If you had a dual boot machine, the steps for copying the TrueType fonts from Windows to Linux might look something like this: (Keep in mind that the steps below assume that you are using the directory name c_drive as the C: drive for WINE.)
MKDIR -P /C_DRIVE/WINDOWS/FONTS
MOUNT /DEV/HDA1 /DOS
CP /DOS/WINDOWS/FONTS /C_DRIVE/WINDOWS/FONTS
CD /C_DRIVE/WINDOWS/FONTS
TTMKFDIR >FONTS.DIR
CHKFONTPATH --ADD /C_DRIVE/WINDOWS/FONTS

At this point, you must restart the font server. You can do so by issuing the following command:
/ETC/RC.D/INIT.D/XFS RESTART

The TrueType fonts should now be accessible to X Windows. One way to tell for sure is by running XFONTSEL to see which font families are available. You can do so with the following command:
XFONTSEL &

Keep in mind that WINE is dependent on both Linux and X Windows. Unless TrueType fonts are functional within X Windows, they will not work with WINE.

Leaving Windows behind for good
As you can see, there are situations where it may be more advantageous to run a Windows application on a Linux box than on a Windows box. In these situations, it is more cost effective and more efficient to use WINE than a Windows emulator. WINE may not be perfect, but if you're intent on running Windows applications while leaving Windows itself behind, WINE may be the way to go.

List All Users in Linux

To list all the users who can access a Linux machine we have to access the /etc/passwd file, which stores information about all registered users of that machine. But it is not really so easy as told above since the file contains many other fields & machine trust accounts & inbuilt accounts.

We'll start by
cat /etc/passwd

As we all know that by default all the users created will have their home directories in /home share so we'll modify our command a bit by using grep. Now it'll be
cat /etc/passwd | grep "/home"

Now we'll get all the user accounts which have their home share in /home.But the only output we need is the list of users & nothing else. So we'll modify our command again
cat /etc/passwd | grep "/home" |cut -d: -f1

Now what we have done is that we have piped the output of previous command to another variable "cut"

What we have done here is we have added cut -d: -f1
-d: means delimiter :
-f1 means display first field of line i.e. username.

So final command is
cat /etc/passwd | grep "/home" |cut -d: -f1
This works until all your users have their home share in /home. If you have defined their home share to some other destination. Modify the above command accordingly.

Howto: Linux Add User To Group

How can I add a user to a group under Linux operating system?

You can use the useradd or usermod commands to add a user to a group. The useradd command creates a new user or update default new user information. The usermod command modifies a user account i.e. it is useful to add user to existing group. There are two types of group. First is primary user group and other is secondary group. All user account related information is stored in /etc/passwd, /etc/shadow and /etc/group files to store user information.

useradd Example - Add A New User To Secondary Group

You need to the useradd command to add new users to existing group (or create a new group and then add user). If group does not exist, create it. The syntax is as follows:
useradd -G {group-name} username
In this example, create a new user called prem and add it to group called developers. First login as a root user (make sure group developers exists), enter:
# grep developers /etc/group
Output:

developers:x:1124:

If you do not see any output then you need to add group developers using groupadd command:
# groupadd developers
Next, add a user called prem to group developers:
# useradd -G developers Prem
Setup password forv user Prem:
# passwd Prem
Ensure that user added properly to group developers:
# id Prem Output:

uid=1122(Prem) gid=1125(Prem) groups=1125(Prem),1124(developers)

Please note that capital G (-G) option add user to a list of supplementary groups. Each group is separated from the next by a comma, with no intervening whitespace. For example, add user jerry to groups admins, ftp, www, and developers, enter:
# useradd -G admins,ftp,www,developers jerry

useradd example - Add a new user to primary group

To add a user tony to group developers use following command:
# useradd -g developers tony
# id tony
Sample outputs:

uid=1123(tony) gid=1124(developers) groups=1124(developers)

Please note that small -g option add user to initial login group (primary group). The group name must exist. A group number must refer to an already existing group.

usermod example - Add a existing user to existing group

Add existing user tony to ftp supplementary/secondary group with usermod command using -a option ~ i.e. add the user to the supplemental group(s). Use only with -G option :
# usermod -a -G ftp tony
Change existing user tony primary group to www:
# usermod -g www tony

Recover root password

How-To: Recover root password under linux with single user mode

It happens sometime that you can't remember root password. On Linux, recovering root password can be done by booting Linux under a specific mode: single user mode.
This tutorial will show how to boot Linux in single user mode when using GRUB and finally how to change root password.
During normal usage, a Linux OS runs under runlevels between 2 and 5 which corresponds to various multi-user modes. Booting Linux under runlevel 1 will allow one to enter into a specific mode, single user mode. Under such a level, you directly get a root prompt. From there, changing root password is a piece of cake.

1. Entering runlevel 1

Some Linux distribution, such as Ubuntu for instance, offer a specific boot menu entry where it is stated "Recovery Mode" or "Single-User Mode". If this is your case, selecting this menu entry will boot your machine into single user mode, you can carry on with the next part. If not, you might want to read this part.
Using GRUB, you can manually edit the proposed menu entry at boot time. To do so, when GRUB is presenting the menu list (you might need to press ESC first), follow those instructions:

• use the arrows to select the boot entry you want to modify.
• press e to edit the entry
• use the arrows to go to kernel line
• press e to edit this entry
• at the end of the line add the word single
• press ESC to go back to the parent menu
• press b to boot this kernel

The kernel should be booting as usual (except for the graphical splash screen you might be used to), and you will finally get a root prompt (sh#).
Here we are, we have gained root access to the filesystem, let's finally change the password.

2. Changing root password

As root, changing password does not ask for your old password, therefore running the command:

# passwd

will prompt you for your new password and will ask you to confirm it to make sure there is no typo.
That's it, you can now reboot your box and gain root access again

Cool Linux command tricks

he Linux command line is one of the most versatile tools you will ever use. It can do just about anything you can image for a machine. With such a large scope of tasks you can imagine just how much there is to learn. So, it’s always good  to have an arsenal of tricks at your fingertips.
So…let’s take a look at some nifty trickery with the Linux command line.

seq
This is one of the coolest (and most useful) tips I have ever come across.  The seq command will print out a sequence of numbers. So if you issue the command:
seq 0 50
You will see the numbers 0-50 printed out on the terminal. Very simple. Sure that’s great but what good is a sequence of numbers? Let’s apply it and find out. Remember you can always declare a value in bash and by making use of the $ symbol you can use variables in your commands. So what happens if you issue the command:
for k in `seq -w 1 50` ; do ssh 192.168.100.$k uptime ; done
What happens is ssh will walk through all the addresses from 192.168.100.1 to 192.168.100.50 until it finds one with an ssh server accepting connections. When it does it will ask you for the users password and then print out the uptime of that machine. Very handy indeed.

How much space left?
Quick, how much space do you have left on your drive(s)?  And where are those drives mounted on? Do you have the answer yet? If you had a terminal window open you could have issued the command df -h and you would have seen, in a user-friendly format, the percentage of your hard disk space that has been used. Very handy command.

Those pesky bash colors
Do you prefer the colors you see in bash? Do you even know about the colors in bash? From the command line issue the command ls you will see that files are black, folders are blue, executables are green (that’s a simplistic explanation). What if those colors bother you (or cause your pretty transparent terminal from giving you a good read on your file listing)? You can turn that off easily from the command by issuing:
ls --color=none
Of course that is a one-time deal. In order to make this permanent you have to edit your ~/.bashrc file. In that file you will see the following entry:
alias ls='ls --color=auto'
Comment out that entry and ls will no longer use color.

Find files modified TODAY
If you have saved a file today and you can’t remember where you saved it, you can use the find command to print out all files modified today. The command:
find ~ -type f -mtime 0
Will print out a listing of all files that were modified on the day the command was issued (today).

Install from source to package
That might not make any sense. It will in a moment. Say you’ve downloaded the source for a package that you want to install, but you want to keep with the standard for your distribution by installing it from a package (so your package manager is aware of it). You can do this with the help of the checkinstall application. This isn’t installed by default, but you can install it with the command sudo apt-get install checkinstall. Once installed you can install from source with the command (from within the source code directory):
./configure && make && checkinstall
This will ask you some questions regarding your distribution and will install the application.

How to mount usb drive in linux

1. Detecting USB hard drive

After you plug in your USB device to your USB port, linux will add new block device into /dev/ directory. At this stage you are not able to use this device as the USB filesystem needs to be mouted before you are able to retrieve any data. To find out what name your block device file have you can run fdisk command:

# fdisk -l 

You will get output similar to this:

Disk /dev/sdb: 60.0 GB, 60060155904 bytes
255 heads, 63 sectors/track, 7301 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Disk identifier: 0x000b2b03

   Device Boot      Start         End      Blocks   Id  System
/dev/sdb1               1        7301    58645251    b  W95 FAT32

2. Creating mount point

Create directory where you want to mount your device:

mkdir /mnt/sdb1 

3. Edit /etc/fstab

To automate this process you can edit /etc/fstab file and add line similar to this:

/dev/sdb1       /mnt/sdb1           vfat    defaults        0       0 

Run mount command to mount all not yet mounted devices. Keep in mind that if you have more different USB devices in you system, device name can vary!!!

# mount -a 

Resize all your images in linux

I love linux only because it makes the work very simple.. So many inbuilt softwares which are commonly needed available in it. One of them is image editing.. Today , i was looking for image resizing software and at last i found an inbuilt tool which does an excellent job..
All you need to know is one command
$ convert -resize 50% input.jpg output.jpg
thats it.. the file input.jpg will be reduced to 50% and will be saved as output.jpg in the same folder .
If you have a collection of images to be resized. Keep it in a single folder and follow this command
$ convert -resize 50% *.jpg output.jpg
It will convert all your images and will save as output0.jpg, output1.jpg etc..
You can vary the resizing percentage according to your interest.
now, if you need to convert a jpg image to png,,just alter the command
$ convert input.jpg output.png

How to find files in linux

These are some of the useful commands to search files in linux system.
Consider we need to list all the mp3 files in our system. Use the following command

find / -name *.mp3

Now, we need to find a file which has the name in which some letters are s and e

find / -name *se*

if we need to search in a particular folder, just include the folder path

find Softwares/ -name *se*

Find command is useful but it will take some time to search the system if it contains too many files. Locate is a very simple and powerful command which can be used in place of find.

To find the file abc.txt command is

locate abc.txt

it will scan the system and list the locations where abc.txt is present.
Now, if we need to search in a specific directory just include the folder name.

locate Softwares/ *.txt

okay then why we should use locate command ? both yields the same result..
Its because locate command is too faster than find command. The reason for that is, there is a background process that runs on your system that essentially finds new files and stores them in a database. when you use the locate command, it then searches the database instead of searching your filesystem while you wait.

How to change file/folder permissions in linux

Recently i crossed through a serious issue of folder permissions.. I installed xampp in /opt folder which is under file system.. And i was not able to add or copy files into that folder. Even in the properties bar the option is shaded as i was not logged on as the root user.. Now, its the time to know how to unlock all permissions.
User permissions can be provided using the command “chmod”. We have to specify for which user we are going to give permission and what permission we are going to approve.
u user/owner
g group
o other
a all
and file permissions are
r read
w write
x execute
what to do?
+ add permission
- remove permission
= set exactly this permission
For example,
$ chmod a+rwx /opt/lampp -R
In the above example i gave permission to all the users for read, write and execute inside lampp folder under /opt. If you add -R the permissions will also get applied for the subfolders. For more details use manual
$ man chmod
Once you finish above tasks we need to solve the phpmyadmin error..  First we have to change permission for my.cnf file. Type this command
$ chmod 644 /opt/lampp/etc/my.cnf
and then open /opt/lampp/phpmyadmin/libraries/Config.class.php . Search for
$this->checkPermissions();
replace with
//$this->checkPermissions();
save the document and restart xampp .

how to use ls commands

Sometimes we need to display only the directories in a folder. At this case use the following command
$ ls -l | egrep ‘^d’
It will display only the directory list with some options..
If you need to see only the files, use -v to get the converse effect of the above command
$ ls -l | egrep -v ‘^d’
Every time we cant execute these big commands. Better we can use alias for these commands.
let me call ldir as list directories lf as list files..
Now, we can create alias as
$ alias ldir=”ls -l | egrep ‘^d’”
and for files
$ alias lf=”ls -l | egrep -v ‘^d’”
Now open the bash profile in vi editore
$ vi .bash_profile
Append the above two alias commands save and close.
Now, check by typing
$ ldir /etc
and
$ lf /etc

How to mount and unmount images in linux

When i was using Win xp i had to create a virtual drive through power iso, alcohol 120,daemon tool or nero smart… Everytime the trial period gets expired and i would be in trouble when i were in need to extract iso..
In linux mounting and unmounting iso images is so simple.. Here to we have some softwares to read iso.. gmountiso and isomaster.. there of few 100 kb size.. but through terminal its too simple..
Mounting:
open the terminal
Login as root by su command
$ su
Password:
Create a directory ie. mount point
$ mkdir /mnt/mountpoint
move to the location where iso is saved and type
$ mount -o loop abc.iso /mnt/mountpoint
We have created a directory named mountpoint and in that directory we have extracted the contents of abc.iso..
Unmounting:
Unmount is so simple.. use umount(its ‘umount’ not ‘unmount’. Be careful while typing )
$umount /mnt/mountpoint
Just specify the directory where we have extracted the iso file…

Enjoy friends and just post your comments ..
and feel free  to ask any question. 

How to format usb in linux using terminal

Hi friends today lets learn about   How to format usb drive or any external device.
lets follow these steps and  learn and update your knowledge with my SpecialSite . of Prem verma.

Here is the step to format your usb drive using linux terminal
Step 1: Insert your usb drive. Wait till it mounts.
Step 2: Login as super user by typing su command
$ su
Password:
Step 3: Use the following command to find the device name
# fdisk -l
check out the device boot name.. for example its /dev/sdb1 in my pc.
Step 4: If you are using Ext3 type following command to format
# mkfs.ext3 /dev/sdb1
Step 5: If you are using FAT type following command to format
# mkfs.vfat /dev/sdb1
Step 6: If you need to label your usb drive use the following command to format and label
# mkfs.vfat -n ‘Label’ -I /dev/sda
Replace Label with the name you are assigning to usb drive.


friends if you have any kind of doubt  feel free and ask your question .
and post your comments and share your knowledge   with us.

A 2 Z LINUX ALL COMMANDS

Below given are the list of Linux commands which starts with A. We have provided a breif description for each command. To know more about each command and its usage try the following.

man command-name

Example:

man accept

 

                                        A
          
accept - accept a connection on a socket
accept - accept a new connection on a socket
access - check user's permissions for a file
access - determine accessibility of a file
access.conf [access] - the login access control table file
aconnect - ALSA sequencer connection manager
acpid - Advanced Configuration and Power Interface event daemon
acpid - ACPI Event Daemon
addr2line - convert addresses into file names and line numbers
addresses - Dumps the Palm Address Book entries to STDOUT in a simple format
agetty - alternative Linux getty
alsactl - advanced controls for ALSA soundcard driver
amidi - read from and write to ALSA RawMIDI ports
amixer - command-line mixer for ALSA soundcard driver
anacron - runs commands periodically
anacron - A cron-like program that can run jobs lost during downtime.
aplay - command-line sound recorder and player for ALSA soundcard driver
aplaymidi - play Standard MIDI Files
apm - interface with the APM subsystem
apm - Alliance ProMotion video driver
apmd - Advanced Power Management (APM) daemon
apmd - Advanced Power Management (APM) BIOS utilities for laptops.
apropos - search the whatis database for strings
ar - create, modify, and extract from archives
ar - create and maintain library archives
arch - print machine architecture
arecord [aplay] - command-line sound recorder and player for ALSA soundcard driver
arecordmidi - record Standard MIDI Files
arp - Linux ARP kernel module
arp - manipulate the system ARP cache
AS [as] - the portable GNU assembler
at - queue, examine or delete jobs for later execution
at - execute commands at a later time
at - Job spooling tools.
at-spi - Assistive Technology Service Provider Interface
at.allow [at] - determine who can submit jobs via at or batch
at.deny [at] - determine who can submit jobs via at or batch
atd - run jobs queued for later execution
atq - queue, examine or delete jobs for later execution
atrm - queue, examine or delete jobs for later execution


                             B
badblocks - search a device for bad blocks
basename -strip directory and suffix from filenames
basename - return non-directory portion of a pathname
basename - Parse pathname components
basename - return the last component of a pathname
bash - GNU Bourne-Again SHell
bash - The GNU
Bourne Again shell (bash) version 3.1.
bash [builtins] - bash built-incommands, see bash(1)
batch - schedule commands to be executedin a batch queue
batch [at] - queue, examine or delete jobs for laterexecution
bc - An arbitrary precision calculator language
bc - arbitrary-precision arithmetic language
bc - GNU's bc (a numeric processing language) and dc (a calculator).
bzcmp

[bzdiff] - compare bzip2 compressed files
bzdiff -compare bzip2 compressed files
bzgrep - search possibly bzip2 compressed files for a regular expression
bzip2 - a block-sorting file compressor, v1.0.3
bzip2 - A file compression utility.
bzip2-libs - Libraries for applications using bzip2
bzless

[bzmore] - file perusal filter for crt viewing of bzip2 compressed text
bzmore - file perusal filter for crt viewing of bzip2 compressed text

                                                  B

c++filt (1) - Demangle C++ and Java symbols
cal (1) - displays a calendar
cal (1p) - print a calendar
cat (1) - concatenate files and print on the standard output
cat (1p) - concatenate and print files
cdda2wav (1) - a sampling utility that dumps CD audio data into wav sound files
cdda2wav (rpm) - A utility for sampling/copying .wav files from digital audio CDs.
cdparanoia (rpm) - A Compact Disc Digital Audio (CDDA) extraction tool (or ripper).
cdparanoia-libs (rpm) - Libraries for libcdda_paranoia (Paranoia III).
cdrdao (1) - writes audio CD-Rs in disc-at-once mode
cdrdao (rpm) - Writes audio CD-Rs in disk-at-once (DAO) mode.
cdrecord (1) - record audio or data Compact Disks or Digital Versatile Disks from a master
cdrecord (rpm) - A command line CD/DVD recording program.
chage (1) - change user password expiry information
chattr (1) - change file attributes on a Linux second extended file system
chfn (1) - change your finger information
chgrp (1) - change group ownership
chgrp (1p) - change the file group ownership
chkconfig (8) - updates and queries runlevel information for system services
chkconfig (rpm) - A system tool for maintaining the /etc/rc*.d hierarchy.
chmod (1) - change file access permissions
chmod (1p) - change the file modes
chmod (2) - change permissions of a file
chmod (3p) - change mode of a file
chown (1) - change file owner and group
chown (1p) - change the file ownership
chown (2) - change ownership of a file
chown (3p) - change owner and group of a file
chpasswd (8) - update passwords in batch mode
chroot (1) - run command or interactive shell with special root directory
chroot (2) - change root directory
chrt (1) - manipulate real-time attributes of a process
chsh (1) - change your login shell
chvt (1) - change foreground virtual terminal
cksum (1) - checksum and count the bytes in a file
cksum (1p) - write file checksums and sizes
clear (1) - clear the terminal screen
cmp (1) - compare two files
cmp (1p) - compare two files
col (1) - filter reverse line feeds from input
colcrt (1) - filter nroff output for CRT previewing
colrm (1) - remove columns from a file
column (1) - columnate lists
comm (1) - compare two sorted files line by line
comm (1p) - select or reject lines common to two files
Compress::Zlib (3pm) - Interface to zlib compression library
cp (1) - copy files and directories
cp (1p) - copy files
cpio (1) - copy files to and from archives
cpio (rpm) - A GNU archiving program.
cpio.h [cpio] (0p) - cpio archive values
cpp (1) - The C Preprocessor
cpp (rpm) - The C Preprocessor.
crontab (1) - maintain crontab files for individual users (ISC Cron V4.1)
crontab (1p) - schedule periodic background work
crontab (5) - tables for driving cron (ISC Cron V4.1)
csplit (1) - split a file into sections determined by context lines
csplit (1p) - split files based on context
ctags (1p) - create a tags file (DEVELOPMENT, FORTRAN)
cupsd (8) - common unix printing system daemon
cupsd.conf [cupsd] (5) - server configuration file for cups
cut (1) - remove sections from each line of files
cut (1p) - cut out selected fields of each line of a file
           D
 date (1) - print or set the system date and time
date (1p) - write the date and time
dd (1) - convert and copy a file
dd (1p) - convert and copy a file
deallocvt (1) - deallocate unused virtual consoles
debugfs (8) - ext2/ext3 file system debugger
depmod (8) - program to generate modules.dep and map files
depmod.conf [depmod] (5) - Configuration file/directory for depmod
depmod.d [depmod] (5) - Configuration file/directory for depmod
devdump [isoinfo] (8) - Utility programs for dumping and verifying iso9660 images
df (1) - report file system disk space usage
df (1p) - report free disk space
diff (1) - find differences between two files
diff (1p) - compare two files
diff-jars (1) - output the differences between two JAR files
diff3 (1) - find differences between three files
dig (1) - DNS lookup utility
dir (1) - list directory contents
dircolors (1) - color setup for ls
dirname (1) - strip non-directory suffix from file name
dirname (1p) - return the directory portion of a pathname
dirname (3p) - report the parent directory name of a file pathname
dirname [basename] (3) - Parse pathname components
dmesg (8) - print or control the kernel ring buffer
dnsdomainname [hostname] (1) - show the system's DNS domain name
doexec (1) - run an executable with an arbitrary argv[0]
domainname [hostname] (1) - show or set the system's NIS/YP domain name
dosfsck (8) - check and repair MS-DOS file systems
du (1) - estimate file space usage
du (1p) - estimate file space usage
dump (8) - ext2/3 filesystem backup
dump (rpm) - Programs for backing up and restoring ext2/ext3 filesystems
dumpe2fs (8) - dump ext2/ext3 filesystem information
dumpkeys (1) - dump keyboard translation tables


                E
e2label (8) - Change the label on an ext2/ext3 filesystem
echo (1) - display a line of text
echo (1p) - write arguments to standard output
echo [builtins] (1) - bash built-in commands, see bash(1)
edquota (8) - edit user quotas
egrep [grep] (1) - print lines matching a pattern
eject (1) - eject removable media
eject (rpm) - A program that ejects removable media using software control.
enable [builtins] (1) - bash built-in commands, see bash(1)
Env (3pm) - perl module that imports environment variables as scalars or arrays
env (1) - run a program in a modified environment
env (1p) - set the environment for command invocation
envsubst (1) - substitutes environment variables in shell format strings
esd (1) - The Enlightened Sound Daemon
esd-config (1) - The Enlightened Sound Daemon
esd-config (1) - The Enlightened Sound Daemon
esdcat (1) - The Enlightened Sound Daemon
esdctl (1) - The Enlightened Sound Daemon
esddsp (1) - attempt to reroute audio device to esd
esddsp [esdplay] (1) - attempt to reroute audio device to esd
esdmon (1) - The Enlightened Sound Daemon
esdrec (1) - The Enlightened Sound Daemon
esdsample (1) - The Enlightened Sound Daemon
ex (1p) - text editor
expand (1) - convert tabs to spaces
expand (1p) - convert tabs to spaces
e2label (8) - Change the label on an ext2/ext3 filesystem
echo (1) - display a line of text
echo (1p) - write arguments to standard output
echo [builtins] (1) - bash built-in commands, see bash(1)
edquota (8) - edit user quotas
egrep [grep] (1) - print lines matching a pattern
eject (1) - eject removable media
eject (rpm) - A program that ejects removable media using software control.
enable [builtins] (1) - bash built-in commands, see bash(1)
Env (3pm) - perl module that imports environment variables as scalars or arrays
env (1) - run a program in a modified environment
env (1p) - set the environment for command invocation
envsubst (1) - substitutes environment variables in shell format strings
esd (1) - The Enlightened Sound Daemon
esd-config (1) - The Enlightened Sound Daemon
esd-config (1) - The Enlightened Sound Daemon
esdcat (1) - The Enlightened Sound Daemon
esdctl (1) - The Enlightened Sound Daemon
esddsp (1) - attempt to reroute audio device to esd
esddsp [esdplay] (1) - attempt to reroute audio device to esd
esdmon (1) - The Enlightened Sound Daemon
esdrec (1) - The Enlightened Sound Daemon
esdsample (1) - The Enlightened Sound Daemon
ex (1p) - text editor
expand (1) - convert tabs to spaces
expand (1p) - convert tabs to spaces
expr (1) - evaluate expressions
expr (1p) - evaluate arguments as an expression

          F

factor (1) - factor numbers
false (1) - do nothing, unsuccessfully
false (1p) - return false value
fc-cache (1) - build font information cache files
fc-list (1) - list available fonts
fdformat (8) - Low-level formats a floppy disk
fdisk (8) - Partition table manipulator for Linux
fetchmail (1) - fetch mail from a POP, IMAP, ETRN, or ODMR-capable server
fetchmail (rpm) - A remote mail retrieval and forwarding utility
fgconsole (1) - print the number of the active VT
fgrep [grep] (1) - print lines matching a pattern
File::Basename (3pm) - Parse file paths into directory, filename and suffix
File::Compare (3pm) - Compare files or filehandles
File::Copy (3pm) - Copy files or filehandles
File::DosGlob (3pm) - DOS like globbing and then some
File::Find (3pm) - Traverse a directory tree
File::Glob (3pm) - Perl extension for BSD glob routine
File::Path (3pm) - create or remove directory trees
File::Spec (3pm) - portably perform operations on file names
File::Spec::Cygwin (3pm) - methods for Cygwin file specs
File::Spec::Epoc (3pm) - methods for Epoc file specs
File::Spec::Functions (3pm) - portably perform operations on file names
File::Spec::Mac (3pm) - File::Spec for Mac OS (Classic)
File::Spec::OS2 (3pm) - methods for OS/2 file specs
File::Spec::Unix (3pm) - File::Spec for Unix, base for other File::Spec modules
File::Spec::VMS (3pm) - methods for VMS file specs
File::Spec::Win32 (3pm) - methods for Win32 file specs
File::Temp (3pm) - return name and handle of a temporary file safely
File::stat (3pm) - by-name interface to Perl's built-in stat() functions
file (1) - determine file type
file (1p) - determine file type
file (rpm) - A utility for determining file types.
file-roller (rpm) - File Roller is a tool for viewing and creating archives
find (1) - search for files in a directory hierarchy
find (1p) - find files
finger (1) - user information lookup program
finger (rpm) - The finger client.
fmt (1) - simple optimal text formatter
fold (1) - wrap each input line to fit in specified width
fold (1p) - filter for folding lines
formail (1) - mail (re)formatter
free (1) - Display amount of free and used memory in the system
free (3p) - free allocated memory
free [malloc] (3) - Allocate and free dynamic memory
fsck (8) - check and repair a Linux file system
ftp (1) - Internet file transfer program
ftp (rpm) - The standard UNIX FTP (File Transfer Protocol) client.
fuser (1) - identify processes using files or sockets
fuser (1p) - list process IDs of all processes that have one or more files open

                                      G
gawk (1) - pattern scanning and processing language
gawk (rpm) - The GNU version of the awk text processing utility.
gawk [pgawk] (1) - pattern scanning and processing language
getent (1) - get entries from administrative database
getkeycodes (8) - print kernel scancode-to-keycode mapping table
gpasswd (1) - administer the /etc/group file
gpg (1) - encryption and signing tool
gpg-pubkey (rpm) - gpg(CentOS-5 Key (CentOS 5 Official Signing Key) <centos-5-key@centos.org>)
gpg-pubkey (rpm) - gpg(Stu Tomlinson <stu@nosnilmot.com>)
gpgv (1) - signature verification tool
gpm (8) - a cut and paste utility and mouse server for virtual consoles
gpm (rpm) - A mouse server for the Linux console.
gpm-root (1) - a default handler for gpm, used to draw menus on the root window
gprof (1) - display call graph profile data
grep (1) - print lines matching a pattern
grep (1p) - search a file for a pattern
grep (rpm) - The GNU versions of grep pattern matching utilities.
groff (1) - front-end for the groff document formatting system
groff (7) - a short reference for the GNU roff language
groff (rpm) - A document formatting system.
groffer (1) - display groff files and man~pages on X and tty
groupadd (8) - create a new group
groupdel (8) - delete a group
groupmod (8) - modify a group
groups (1) - print the groups a user is in
grpck (8) - verify integrity of group files
grpconv [pwconv] (8) - convert to and from shadow passwords and groups
gs (1) - Ghostscript (PostScript and PDF language interpreter and previewer)
gunzip [gzip] (1) - compress or expand files
gzexe (1) - compress executable files in place
gzip (1) - compress or expand files
gzip (rpm) - The GNU data compression program.

       H
halt (8) - stop the system
hdparm (8) - get/set hard disk parameters
hdparm (rpm) - A utility for displaying and/or setting hard disk parameters.
head (1) - output the first part of files
head (1p) - copy the first part of files
hexdump (1) - ascii, decimal, hexadecimal, octal dump
host (1) - DNS lookup utility
host.conf [host] (5) - resolver configuration file
hostid (1) - print the numeric identifier for the current host
hostname (1) - show or set the system's host name
htdigest (1) - manage user files for digest authentication
hwclock (8) - query and set the hardware clock (RTC)
 
                I

iconv (1) - Convert encoding of given files from one encoding to another
iconv (1p) - codeset conversion
iconv (3) - perform character set conversion
iconv (3p) - codeset conversion function
iconv.h [iconv] (0p) - codeset conversion facility
id (1) - print user identity
id (1p) - return user identity
ifconfig (8) - configure a network interface
info (1) - read Info documents
info (5) - readable online documentation
info (rpm) - A stand-alone TTY-based reader for GNU texinfo documentation.
init (8) - process control initialization
insmod (8) - simple program to insert a module into the Linux Kernel
install (1) - copy files and set attributes
install-catalog (8) - Manage a SGML or XML centralized catalog
install-datebook (1) - installs a new datebook entry onto your Palm handheld
install-expenses (1) - Install an expense record from various parameters and arguments passed at connection time
install-hinote (1) - installs a new Hi-Note entry onto your Palm handheld
install-info (1) - update info/dir entries
install-memo (1) - installs a new Memo Pad entry onto your Palm handheld
install-netsync (1) - reads or sets the Network Preferences information on a Palm Device
install-todo (1) - Updates the Palm ToDo list with one new entry
install-user (1) - reads or sets a Palm User and UserID on a Palm Device
ipcrm (1p) - remove an XSI message queue, semaphore set, or shared memory segment identifier
ipcrm (8) - remove a message queue, semaphore set or shared memory id
ipcs (1p) - report XSI interprocess communication facilities status
ipcs (8) - provide information on ipc facilities
iptables (8) - administration tool for IPv4 packet filtering and NAT
iptables (rpm) - Tools for managing Linux kernel packet filtering capabilities.
iptables-ipv6 (rpm) - IPv6 support for iptables.
iptables-restore (8) - Restore IP Tables
iptables-save (8) - Save IP Tables
iptables-restore (8) - Restore IP Tables
iptables-save (8) - Save IP Tables
isodump (5) - format of IEEE 1394 isochronous packets dump file
isodump [isoinfo] (8) - Utility programs for dumping and verifying iso9660 images
isoinfo (8) - Utility programs for dumping and verifying iso9660 images
isosize (8) - outputs the length of a iso9660 file system
isovfy [isoinfo] (8) - Utility programs for dumping and verifying iso9660 images
  
               J

join (1) - join lines of two files on a common field
join (1p) - relational database operator

                              K
kbd_mode (1) - report or set the keyboard mode
kbdrate (8) - reset the keyboard repeat rate and delay time
kill (1) - terminate a process
kill (1p) - terminate or signal processes
kill (2) - send signal to a process
kill (3p) - send a signal to a process or a group of processes
kill [builtins] (1) - bash built-in commands, see bash(1)
killall (1) - kill processes by name
klogd (8) - Kernel Log Daemon
kudzu (8) - detects and configures new and/or changed hardware on a system
kudzu (rpm) - The CentOS hardware probing tool.

                          L

last (1) - show listing of last logged in users
lastb [last] (1) - show listing of last logged in users
lastlog (8) - reports the most recent login of all users or of a given user
ld (1) - The GNU linker
ld (8) - linux.so* - dynamic linker/loader
ld.so [ld] (8) - linux.so* - dynamic linker/loader
ldd (1) - print shared library dependencies
less (1) - opposite of more
less (3pm) - perl pragma to request less of something from the compiler
less (rpm) - A text file browser similar to more, but better.
lesskey (1) - specify key bindings for less
lftp (1) - Sophisticated file transfer program
lftp (rpm) - A sophisticated file transfer program
lftpget (1) - get a file with lftp(1)
link (1) - call the link function to create a link to a file
link (1p) - call link function
link (2) - make a new name for a file
link (3p) - link to a file
ln (1) - make links between files
ln (1p) - link files
loadkeys (1) - load keyboard translation tables
Locale::Constants (3pm) - constants for Locale codes
Locale::Country (3pm) - ISO codes for country identification (ISO 3166)
Locale::Currency (3pm) - ISO three letter codes for currency identification (ISO 4217)
Locale::Language (3pm) - ISO two letter codes for language identification (ISO 639)
Locale::Maketext (3pm) - framework for localization
Locale::Script (3pm) - ISO codes for script identification (ISO 15924)
locale (1) - Get locale - specific information
locale (1p) - get locale - specific information
locale (3pm) - Perl pragma to use and avoid POSIX locales for built-in operations
locale (5) - Describes a locale definition file
locale (7) - Description of multi-language support
locale.h [locale] (0p) - category macros
locate (1) - find files by name
lockfile (1) - conditional semaphore-file creator
logger (1) - a shell command interface to the syslog(3) system log module
logger (1p) - log messages
login (1) - sign on
login (3) - write utmp and wtmp entries
login.defs [login] (5) - shadow password suite configuration
logname (1) - print user's login name
logname (1p) - return the user's login name
logrotate (8) - rotates, compresses, and mails system logs
logrotate (rpm) - Rotates, compresses, removes and mails system log files.
look (1) - display lines beginning with a given string
look [Search::Dict] (3pm) - search for key in dictionary file
losetup (8) - set up and control loop devices
lpadmin (8) - configure cups printers and classes
lpinfo (8) - show available devices or drivers
lpmove (8) - move a job or all jobs to a new destination
lpq [lpq-cups] (1) - show printer queue status
lpr [lpr-cups] (1) - print files
lprm [lprm-cups] (1) - cancel print jobs
lpstat [lpstat-cups] (1) - print cups status information
ls (1) - list directory contents
ls (1p) - list directory contents
lsattr (1) - list file attributes on a Linux second extended file system
lspci (8) - list all PCI devices
lsmod (8) - program to show the status of modules in the Linux Kernel
lsusb (8) - list USB devices
  
         M
M4 [m4] (1) - manual page for M4 1.4.5
m4 (1p) - macro processor (DEVELOPMENT)
m4 (rpm) - The GNU macro processor.
Mail::SpamAssassin (3pm) - Spam detector and markup engine
Mail::SpamAssassin::AICache (3pm) - provide access to cached information for ArchiveIterator
Mail::SpamAssassin::ArchiveIterator (3pm) - find and process messages one at a time
Mail::SpamAssassin::AutoWhitelist (3pm) - auto-whitelist handler for SpamAssassin
Mail::SpamAssassin::Bayes (3pm) - determine spammishness using a Bayesian classifier
Mail::SpamAssassin::BayesStore (3pm) - Bayesian Storage Module
Mail::SpamAssassin::BayesStore::MySQL (3pm) - MySQL Specific Bayesian Storage Module Implementation
Mail::SpamAssassin::BayesStore::PgSQL (3pm) - PostgreSQL Specific Bayesian Storage Module Implementation
Mail::SpamAssassin::BayesStore::SQL (3pm) - SQL Bayesian Storage Module Implementation
Mail::SpamAssassin::Client (3pm) - Client for spamd Protocol
Mail::SpamAssassin::Conf (3pm) - SpamAssassin configuration file
Mail::SpamAssassin::Conf::LDAP (3pm) - load SpamAssassin scores from LDAP database
Mail::SpamAssassin::Conf::Parser (3pm) - parse SpamAssassin configuration
Mail::SpamAssassin::Conf::SQL (3pm) - load SpamAssassin scores from SQL database
Mail::SpamAssassin::DnsResolver (3pm) - DNS resolution engine
Mail::SpamAssassin::Logger (3pm) - SpamAssassin logging module
Mail::SpamAssassin::Logger::File (3pm) - log to file
Mail::SpamAssassin::Logger::Stderr (3pm) - log to standard error
Mail::SpamAssassin::Logger::Syslog (3pm) - log to syslog
Mail::SpamAssassin::Message (3pm) - decode, render, and hold an RFC-2822 message
Mail::SpamAssassin::Message::Metadata (3pm) - extract metadata from a message
Mail::SpamAssassin::Message::Node (3pm) - decode, render, and make available MIME message parts
Mail::SpamAssassin::PerMsgLearner (3pm) - per-message status (spam or not-spam)
Mail::SpamAssassin::PerMsgStatus (3pm) - per-message status (spam or not-spam)
Mail::SpamAssassin::PersistentAddrList (3pm) - persistent address list base class
Mail::SpamAssassin::Plugin (3pm) - SpamAssassin plugin base class
Mail::SpamAssassin::Plugin::AWL (3pm) - Normalize scores via auto-whitelist
Mail::SpamAssassin::Plugin::AccessDB (3pm) - check message against Access Database
Mail::SpamAssassin::Plugin::AutoLearnThreshold (3pm) - threshold-based discriminator for Bayes auto-learning
Mail::SpamAssassin::Plugin::DCC (3pm) - perform DCC check of messages
Mail::SpamAssassin::Plugin::DKIM (3pm) - perform DKIM verification tests
Mail::SpamAssassin::Plugin::DomainKeys (3pm) - perform DomainKeys verification tests
Mail::SpamAssassin::Plugin::Hashcash (3pm) - perform hashcash verification tests
Mail::SpamAssassin::Plugin::Pyzor (3pm) - perform Pyzor check of messages
Mail::SpamAssassin::Plugin::Razor2 (3pm) - perform Razor check of messages
Mail::SpamAssassin::Plugin::ReplaceTags (3pm) - tags for SpamAssassin rules
Mail::SpamAssassin::Plugin::SPF (3pm) - perform SPF verification tests
Mail::SpamAssassin::Plugin::SpamCop (3pm) - perform SpamCop reporting of messages
Mail::SpamAssassin::Plugin::TextCat (3pm) - TextCat language guesser
Mail::SpamAssassin::Plugin::WhiteListSubject (3pm) - whitelist by Subject header
Mail::SpamAssassin::PluginHandler (3pm) - SpamAssassin plugin handler
Mail::SpamAssassin::SQLBasedAddrList (3pm) - SpamAssassin SQL Based Auto Whitelist
Mail::SpamAssassin::SubProcBackChannel (3pm) - back-channel for communication between a master and multiple slave processes
Mail::SpamAssassin::Timeout (3pm) - safe, reliable timeouts in perl
Mail::SpamAssassin::Util (3pm) - utility functions
Mail::SpamAssassin::Util::Progress (3pm) - Progress bar support for SpamAssassin
mail (1) - send and receive mail
mailq (1) - print the mail queue

mailstats (8) - display mail statistics
mailto.conf [mailto] (5) - configuration file for cups email notifier
make (1) - GNU make utility to maintain groups of programs
make (1p) - maintain, update, and regenerate groups of programs (DEVELOPMENT)
make (rpm) - A GNU tool which simplifies the build process for users.
makemap (8) - create database maps for sendmail
man (1) - format and display the on-line manual pages
man (1p) - display system documentation
man (7) - macros to format man pages
man (rpm) - A set of documentation tools: man, apropos and whatis.
man-pages (rpm) - Man (manual) pages from the Linux Documentation Project.
man.config [man] (5) - configuration data for man
mattrib (1) - change MSDOS file attribute flags
mbadblocks (1) - tests a floppy disk, and marks the bad blocks in the FAT
mcat (1) - dump raw disk image
mcd (1) - change MSDOS directory
mcopy (1) - copy MSDOS files to/from Unix
md5sum (1) - compute and check MD5 message digest
mdeltree (1) - recursively delete an MSDOS directory and its contents
mdir (1) - display an MSDOS directory
mdu (1) - display the amount of space occupied by an MSDOS directory
mesg (1) - control write access to your terminal
mesg (1p) - permit or deny messages
mformat (1) - add an MSDOS filesystem to a low-level formatted floppy disk
minfo (1) - print the parameters of a MSDOS filesystem
mkdir (1) - make directories
mkdir (1p) - make directories
mkdir (2) - create a directory
mkdir (3p) - make a directory
mkdosfs (8) - create an MS-DOS file system under Linux
mke2fs (8) - create an ext2/ext3 filesystem
mke2fs [mkfs] (8) - create an ext2/ext3 filesystem
mke2fs.conf [mke2fs] (5) - Configuration file for mke2fs
mkfifo (1) - make FIFOs (named pipes)
mkfifo (1p) - make FIFO special files
mkfifo (3) - make a FIFO special file (a named pipe)
mkfifo (3p) - make a FIFO special file
mkfs (8) - build a Linux file system
mkisofs (8) - create an hybrid ISO9660/JOLIET/HFS filesystem with optional Rock Ridge attributes
mkisofs (rpm) - Creates an image of an ISO9660 filesystem.
mklost+found (8) - create a lost+found directory on a mounted Linux second extended file system
mkmanifest (1) - makes list of file names and their DOS 8+3 equivalent
mknod (1) - make block or character special files
mknod (2) - create a special or ordinary file
mknod (3p) - make a directory, a special file, or a regular file
mkswap (8) - set up a Linux swap area
mktemp (1) - make temporary filename (unique)
mktemp (3) - make a unique temporary filename
mktemp (3p) - make a unique filename (LEGACY)
mktemp (rpm) - A small utility for safely making /tmp files.
mlabel (1) - make an MSDOS volume label
mmd (1) - make an MSDOS subdirectory
mmount (1) - mount an MSDOS disk
mmove (1) - move or rename an MSDOS file or subdirectory
modinfo (8) - program to show information about a Linux Kernel module
modprobe (8) - program to add and remove modules from the Linux Kernel
modprobe.conf [modprobe] (5) - Configuration file/directory for modprobe
modprobe.d [modprobe] (5) - Configuration file/directory for modprobe
more (1) - file perusal filter for crt viewing
more (1p) - display files on a page-by-page basis
mount (2) - mount and unmount filesystems
mount (8) - mount a file system
mount.cifs [mount] (8) - mount using the Common Internet File System (CIFS)
mount.nfs [mount] (8) - mount a Network File System
mount.nfs4 [mount] (8) - mount a Network File System
mpartition (1) - partition an MSDOS hard disk
mrd (1) - remove an MSDOS subdirectory
mren (1) - rename an existing MSDOS file
mshowfat (1) - shows FAT clusters allocated to file
mtools (1) - utilities to access DOS disks in Unix
mtools (rpm) - Programs for accessing MS-DOS disks without mounting the disks.
mtools.conf [mtools] (5) - mtools configuration files
mtoolstest (1) - tests and displays the configuration
mtype (1) - display contents of an MSDOS file
mv (1) - move (rename) files
mv (1p) - move files
mzip (1) - change protection mode and eject disk on Zip/Jaz drive

  N
namei (1) - follow a pathname until a terminal point is found
nameif (8) - name network interfaces based on MAC addresses
netstat (8) - Print network connections, routing tables, interface statistics, masquerade connections, and multicast memberships
newaliases (1) - rebuild the data base for the mail aliases file
newgrp (1) - log in to a new group
newgrp (1p) - change to a new group
newusers (8) - update and create new users in batch
nfsd (7) - special filesystem for controlling Linux NFS server
nfsstat (8) - list NFS statistics
nice (1) - run a program with modified scheduling priority
nice (1p) - invoke a utility with an altered nice value
nice (2) - change process priority
nice (3p) - change the nice value of a process
nm (1) - list symbols from object files
nm (1p) - write the name list of an object file (DEVELOPMENT)
nohup (1) - run a command immune to hangups, with output to a non-tty
nohup (1p) - invoke a utility immune to hangups
nslookup (1) - query Internet name servers interactively
nsupdate (8) - Dynamic DNS update utility


  O
objcopy (1) - copy and translate object files
objdump (1) - display information from object files
od (1) - dump files in octal and other formats
od (1p) - dump files in various formats
openvt (1) - start a program on a new virt

 P
passwd (1) - update a user's authentication tokens(s)
passwd (5) - password file
passwd (rpm) - The passwd utility for setting/changing passwords using PAM
passwd [sslpasswd] (1ssl) - compute password hashes
paste (1) - merge lines of files
paste (1p) - merge corresponding or subsequent lines of files
patch (1) - apply a diff file to an original
patch (1p) - apply changes to files
patch (rpm) - The GNU patch command, for modifying/upgrading files.
pathchk (1) - check whether file names are valid or portable
pathchk (1p) - check pathnames
perl (1) - Practical Extraction and Report Language
perl (rpm) - The Perl programming language
perl-Archive-Tar (rpm) - A module for Perl manipulation of .tar files
perl-Compress-Zlib (rpm) - A module providing Perl interfaces to the zlib compression library.
perl-Digest-HMAC (rpm) - Digest-HMAC Perl module
perl-Digest-SHA1 (rpm) - Digest-SHA1 Perl module
perl-HTML-Parser (rpm) - Perl module for parsing HTML
perl-HTML-Tagset (rpm) - HTML::Tagset - data tables useful in parsing HTML
perl-IO-Socket-INET6 (rpm) - Perl Object interface for AF_INET|AF_INET6 domain sockets
perl-IO-Socket-SSL (rpm) - Perl library for transparent SSL
perl-IO-Zlib (rpm) - Perl IO:: style interface to Compress::Zlib
perl-Net-DNS (rpm) - DNS resolver modules for Perl
perl-Net-IP (rpm) - Perl module for manipulation of IPv4 and IPv6 addresses
perl-Net-SSLeay (rpm) - Perl extension for using OpenSSL
perl-Socket6 (rpm) - IPv6 related part of the C socket.h defines and structure manipulators
perl-String-CRC32 (rpm) - Perl interface for cyclic redundency check generation
ping (8) - send ICMP ECHO_REQUEST to network hosts
pinky (1) - lightweight finger
pmap (1) - report memory map of a process
portmap (8) - DARPA port to RPC program number mapper
portmap (rpm) - A program which manages RPC connections.
poweroff [halt] (8) - stop the system
pppd (8) - Point-to-Point Protocol Daemon
pr (1) - convert text files for printing
pr (1p) - print files
praliases (8) - display system mail aliases
printenv (1) - print all or part of environment
printf (1) - format and print data
printf (1p) - write formatted output
printf (3) - formatted output conversion
printf (3p) - print formatted output
printf [builtins] (1) - bash built-in commands, see bash(1)
ps (1) - report a snapshot of the current processes
ps (1p) - report process status
ptx (1) - produce a permuted index of file contents
pwck (8) - verify integrity of password files
pwconv (8) - convert to and from shadow passwords and groups
pwd (1) - print name of current/working directory
pwd (1p) - return working directory name
pwd [builtins] (1) - bash built-in commands, see bash(1)
pwd.h [pwd] (0p) - password structure
python (1) - an interpreted, interactive, object-oriented programming language
python (rpm) - An interpreted, interactive, object-oriented programming language.
python-elementtree (rpm) - Fast XML parser and writer
python-numeric (rpm) - Numerical Extension to Python
python-sqlite (rpm) - Python bindings for sqlite.
python-urlgrabber (rpm) - A high-level cross-protocol url-grabber

 Q

quota (1) - display disk usage and limits
quota (rpm) - System administration tools for monitoring users' disk usage.
quotacheck (8) - scan a filesystem for disk usage, create, check and repair quota files
quotaon (8) - turn filesystem quotas on and off
quotaoff [quotaon] (8) - turn filesystem quotas on and off
quotastats (8) - Program to query quota statistics
 R
ranlib (1) - generate index to archive
rcp (1) - remote file copy
rdate (1) - get the time via the network
rdate (rpm) - Tool for getting the date/time from a remote machine.
rdev (8) - query/set image root device, RAM disk size, or video mode
rdist (1) - remote file distribution client program
rdist (rpm) - Maintains identical copies of files on multiple machines.
rdistd [rdist] (8) - remote file distribution server program
readcd (1) - read or write data Compact Discs
readelf (1) - Displays information about ELF files
readlink (1) - display value of a symbolic link
readlink (2) - read value of a symbolic link
readlink (3p) - read the contents of a symbolic link
reboot (2) - reboot or enable/disable Ctrl-Alt-Del
reboot [halt] (8) - stop the system
rename (1) - Rename files
rename (2) - change the name or location of a file
rename (3p) - rename a file
renice (8) - alter priority of running processes
repquota (8) - summarize quotas for a filesystem
reset [tput] (1) - initialize a terminal or query terminfo database
reset [tset] (1) - terminal initialization
resize2fs (8) - ext2/ext3 file system resizer
restore (8) - restore files or file systems from backups made with dump
rev (1) - reverse lines of a file
rexec (3) - return stream to a remote command
rlogin (1) - remote login
rm (1) - remove files or directories
rm (1p) - remove directory entries
rmail (8) - handle remote mail received via uucp
rmdir (1) - remove empty directories
rmdir (1p) - remove directories
rmdir (2) - delete a directory
rmdir (3p) - remove a directory
rmmod (8) - simple program to remove a module from the Linux Kernel
route (8) - show / manipulate the IP routing table
rpcinfo (8) - report RPC information
rpm (8) - RPM Package Manager
rpm (rpm) - The RPM package management system.
rpm-libs (rpm) - Libraries for manipulating RPM packages.
rpm-python (rpm) - Python bindings for apps which will manipulate RPM packages.
rsh (1) - remote shell
rsh (rpm) - Clients for remote access commands (rsh, rlogin, rcp).
rsh [ksh] (1) - shell, the
rsync (1) - faster, flexible replacement for rcp
rsync (rpm) - A program for synchronizing files over a network.





 S

sane-find-scanner (1) - find SCSI and USB scanners and their device files
scanadf (1) - acquire multiple images from a scanner equipped with an ADF
scanimage (1) - scan an image
scp (1) - secure copy (remote file copy program)
script (1) - make typescript of terminal session
sdiff (1) - find differences between two files and merge interactively
sed (1) - stream editor for filtering and transforming text
sed (1p) - stream editor
sed (rpm) - A GNU stream text editor.
sendmail (8) - an electronic mail transport agent
sendmail (rpm) - A widely used Mail Transport Agent (MTA).
sensors (1) - printing sensors information
sensors-detect (8) - detect hardware monitoring chips
sensors.conf [sensors] (5) - libsensors configuration file
seq (1) - print a sequence of numbers
setkeycodes (8) - load kernel scancode-to-keycode mapping table entries
setleds (1) - set the keyboard leds
setmetamode (1) - define the keyboard meta key handling
setquota (8) - set disk quotas
setsid (2) - creates a session and sets the process group ID
setsid (3p) - create session and set process group ID
setsid (8) - run a program in a new session
setterm (1) - set terminal attributes
sftp (1) - secure file transfer program
sftp-server (8) - SFTP server subsystem
sh (1p) - shell, the standard command language interpreter
sha1sum (1) - compute and check SHA1 message digest
showkey (1) - examine the codes sent by the keyboard
showmount (8) - show mount information for an NFS server
shred (1) - overwrite a file to hide its contents, and optionally delete it
shutdown (2) - shut down part of a full-duplex connection
shutdown (3p) - shut down socket send and receive operations
shutdown (8) - bring the system down
size (1) - list section sizes and total size
skill (1) - send a signal or report process status
slabtop (1) - display kernel slab cache information in real time
slattach (8) - attach a network interface to a serial line
sleep (1) - delay for a specified amount of time
sleep (1p) - suspend execution for an interval
sleep (3) - Sleep for the specified number of seconds
sleep (3p) - suspend execution for an interval of time
snice [skill] (1) - send a signal or report process status
sort (1) - sort lines of text files
sort (1p) - sort, merge, or sequence check text files
sort (3pm) - perl pragma to control sort() behaviour
split (1) - split a file into pieces
split (1p) - split files into pieces
ssh (1) - OpenSSH SSH client (remote login program)
ssh [slogin] (1) - OpenSSH SSH client (remote login program)
ssh-add (1) - adds RSA or DSA identities to the authentication agent
ssh-agent (1) - authentication agent
ssh-copy-id (1) - install your identity.pub in a remote machine's authorized_keys
ssh-keygen (1) - authentication key generation, management and conversion
ssh-keyscan (1) - gather ssh public keys
ssh-keysign (8) - ssh helper program for hostbased authentication
ssh-add (1) - adds RSA or DSA identities to the authentication agent
ssh-agent (1) - authentication agent
ssh-keygen (1) - authentication key generation, management and conversion
ssh-keyscan (1) - gather ssh public keys
sshd (8) - OpenSSH SSH daemon
stat (1) - display file or file system status
stat (2) - get file status
stat (3p) - get file status
strings (1) - print the strings of printable characters in files
strings (1p) - find printable strings in files
strings.h [strings] (0p) - string operations
strip (1) - Discard symbols from object files
strip (1p) - remove unnecessary information from executable files (DEVELOPMENT)
stty (1) - change and print terminal line settings
stty (1p) - set the options for a terminal
stty [unimplemented] (2) - unimplemented system calls
su (1) - run a shell with substitute user and group IDs
sudo (8) - execute a command as another user
sudo (rpm) - Allows restricted root access for specified users.
sudo [sudoedit] (8) - execute a command as another user
sum (1) - checksum and count the blocks in a file
swapoff [swapon] (2) - start/stop swapping to file/device
swapoff [swapon] (8) - enable/disable devices and files for paging and swapping
swapon (2) - start/stop swapping to file/device
swapon (8) - enable/disable devices and files for paging and swapping
sync (1) - flush file system buffers
sync (2) - commit buffer cache to disk
sync (3p) - schedule file system updates
sync (8) - synchronize data on disk with memory
sysctl (2) - read/write system parameters
sysctl (8) - configure kernel parameters at runtime
sysctl.conf [sysctl] (5) - sysctl(8) preload/configuration file
sysklogd (8) - Linux system logging utilities
sysklogd (rpm) - System logging and kernel message trapping daemons.
T
tac (1) - concatenate and print files in reverse
tail (1) - output the last part of files
tail (1p) - copy the last part of a file
tailf (1) - follow the growth of a log file
talk (1) - talk to another user
talk (1p) - talk to another user
talk (rpm) - Talk client for one-on-one Internet chatting.
tar (1) - The GNU version of the tar archiving utility
tar (rpm) - A GNU file archiving program
tar.h [tar] (0p) - extended tar definitions
taskset (1) - retrieve or set a processes's CPU affinity
tcpd (8) - access control facility for internet services
tcpdump (8) - dump traffic on a network
tcpdump (rpm) - A network traffic monitoring tool.
tcpslice (8) - extract pieces of and/or glue together tcpdump files
tee (1) - read from standard input and write to standard output and files
tee (1p) - duplicate standard input
tee (2) - duplicating pipe content
telinit [init] (8) - process control initialization
telnet (1) - user interface to the TELNET protocol
telnet (rpm) - The client program for the telnet remote login protocol.
Test (3pm) - provides a simple framework for writing test scripts
Test [Mail::SpamAssassin::Plugin::Test] (3pm) - test plugin
Test::Builder (3pm) - Backend for building test libraries
Test::Builder::Module (3pm) - Base class for test modules
Test::Builder::Tester (3pm) - test testsuites that have been built with Test::Builder
Test::Builder::Tester::Color (3pm) - turn on colour in Test::Builder::Tester
Test::Harness (3pm) - Run Perl standard test scripts with statistics
Test::Harness::Assert (3pm) - simple assert
Test::Harness::Iterator (3pm) - Internal Test::Harness Iterator
Test::Harness::Point (3pm) - object for tracking a single test point
Test::Harness::Straps (3pm) - detailed analysis of test results
Test::Harness::TAP (3pm) - Documentation for the TAP format
Test::More (3pm) - yet another framework for writing test scripts
Test::Simple (3pm) - Basic utilities for writing tests
Test::Tutorial (3pm) - A tutorial about writing really basic tests
test (1) - check file types and compare values
test (1p) - evaluate expression
test [builtins] (1) - bash built-in commands, see bash(1)
Time::HiRes (3pm) - High resolution alarm, sleep, gettimeofday, interval timers
Time::Local (3pm) - efficiently compute time from local and GMT time
Time::gmtime (3pm) - by-name interface to Perl's built-in gmtime() function
Time::localtime (3pm) - by-name interface to Perl's built-in localtime() function
Time::tm (3pm) - internal object used by Time::gmtime and Time::localtime
time (1) - time a simple command or give resource usage
time (1p) - time a simple command
time (2) - get time in seconds
time (3p) - get time
time (7) - overview of time
time (rpm) - A GNU utility for monitoring a program's use of system resources.
time.conf [time] (5) - configuration file for the pam_time module
time.h [time] (0p) - time types
tload (1) - graphic representation of system load average
tmpwatch (8) - removes files which haven't been accessed for a period of time
tmpwatch (rpm) - A utility for removing files based on when they were last accessed.
top (1) - display Linux tasks
touch (1) - change file timestamps
touch (1p) - change file access and modification times
tr (1) - translate or delete characters
tr (1p) - translate characters
tracepath (8) - traces path to a network host discovering MTU along this path
traceroute (8) - print the route packets trace to network host
traceroute (rpm) - Traces the route taken by packets over an IPv4/IPv6 network
troff (1) - the troff processor of the groff text formatting system
true (1) - do nothing, successfully
true (1p) - return true value
tset (1) - terminal initialization
tsort (1) - perform topological sort
tsort (1p) - topological sort
tty (1) - print the file name of the terminal connected to standard input
tty (1p) - return user's terminal name
tty (4) - controlling terminal
tty ioctl [tty_ioctl] (4) - ioctls for terminals and serial lines
tune2fs (8) - adjust tunable filesystem parameters on ext2/ext3 filesystems
tunelp (8) - set various parameters for the lp device





 U 

ul (1) - do underlining
umount (8) - unmount file systems
umount [mount] (2) - mount and unmount filesystems
umount.cifs [umount] (8) - for normal, non-root users, to unmount their own Common Internet File System (CIFS) mounts
umount.nfs [umount] (8) - unmount a Network File System
umount.nfs4 [umount] (8) - unmount a Network File System
uname (1) - print system information
uname (1p) - return system name
uname (2) - get name and information about current kernel
uname (3p) - get the name of the current system
unexpand (1) - convert spaces to tabs
unexpand (1p) - convert spaces to tabs
unicode_start (1) - put keyboard and console in unicode mode
unicode_stop (1) - revert keyboard and console from unicode mode
uniq (1) - report or omit repeated lines
uniq (1p) - report or filter out repeated lines in a file
uptime (1) - Tell how long the system has been running
useradd (8) - create a new user or update default new user information
userdel (8) - delete a user account and related files
usermod (8) - modify a user account
users (1) - print the user names of users currently logged in to the current host
usleep (1) - sleep some number of microseconds
usleep (3) - suspend execution for microsecond intervals
usleep (3p) - suspend execution for an interval
uudecode (1p) - decode a binary file
uuencode (1p) - encode a binary file
uuidgen (1) - command-line utility to create a new UUID valueV
vdir (1) - list directory contents
vi (1p) - screen-oriented (visual) display editor
vim (1) - Vi IMproved, a programmers text editor
vim-common (rpm) - The common files needed by any version of the VIM editor.
vim-enhanced (rpm) - A version of the VIM editor which includes recent enhancements.
vim-minimal (rpm) - A minimal version of the VIM editor.
vmstat (8) - Report virtual memory statistics
volname (1) - return volume name
 W 

w (1) - Show who is logged on and what they are doing
warnquota (8) - send mail to users over quota
watch (1) - execute a program periodically, showing output fullscreen
wc (1) - print the number of newlines, words, and bytes in files
wc (1p) - word, line, and byte or character count
Wget [wget] (1) - The non-interactive network downloader
wget (rpm) - A utility for retrieving files using the HTTP or FTP protocols.
whatis (1) - search the whatis database for complete words
whereis (1) - locate the binary, source, and manual page files for a command
which (1) - shows the full path of (shell) commands
which (rpm) - Displays where a particular program in your path is located.
who (1) - show who is logged on
who (1p) - display who is on the system
whoami (1) - print effective userid
write (1) - send a message to another user
write (1p) - write to another user
write (2) - write to a file descriptor
write (3p) - write on a file




X

xargs (1) - build and execute command lines from standard input
xargs (1p) - construct argument lists and invoke utility




 Y
yacc (1p) - yet another compiler compiler (DEVELOPMENT)
yes (1) - output a string repeatedly until killed
ypbind (8) - NIS binding process
ypbind (rpm) - The NIS daemon which binds NIS clients to an NIS domain.
ypcat (1) - print values of all keys in a NIS database
ypmatch (1) - print the values of one or more keys from a NIS map
yppasswd (1) - change your password in the NIS database
yppoll (8) - return version and master server of a NIS map
ypset (8) - bind ypbind to a particular NIS server
yptest (8) - test NIS configuration
ypwhich (1) - return name of NIS server or map master




 Z
  
zcat (1p) - expand and concatenate data
zcat [gzip] (1) - compress or expand files
zcmp [zdiff] (1) - compare compressed files
zdiff (1) - compare compressed files
zdump (8) - time zone dumper
zforce (1) - force a '.gz' extension on all gzip files
zgrep (1) - search possibly compressed files for a regular expression
zic (8) - time zone compiler
zless (1) - file perusal filter for crt viewing of compressed text
zmore (1) - file perusal filter for crt viewing of compressed text
znew (1) - recompress .Z files to .gz files