[root@Thiyag/]# getsebool -a | grep ftp
allow_ftpd_anon_write –> off
allow_ftpd_full_access –> off
allow_ftpd_use_cifs –> off
allow_ftpd_use_nfs –> off
ftp_home_dir –> off
ftpd_connect_db –> off
ftpd_use_passive_mode –> off
httpd_enable_ftp_server –> off
tftp_anon_write –> off

[root@Thiyag/]# setsebool -P ftp_home_dir on

[root@Thiyag/]# getsebool -a | grep ftp
allow_ftpd_anon_write –> off
allow_ftpd_full_access –> off
allow_ftpd_use_cifs –> off
allow_ftpd_use_nfs –> off
ftp_home_dir –> on
ftpd_connect_db –> off
ftpd_use_passive_mode –> off
httpd_enable_ftp_server –> off
tftp_anon_write –> off

Try to login over FTP again and you should have a success.

UUID is a 128-bit string that is used for making the Linux hard disk management simple. If you look at /etc/fstab file in your Linux computer, you find the entry in the following format, in place of the familiar hard drive designation:

UUID=62fa5eac-3df4-448d-a576-916dd5b432f2

In comparison to the traditional hard drive identification techniques, UUID is quite easy and reliable. For instance, in the traditional Linux systems, when you try to insert a new hard drive in a system that already has two hard drives, the drive is inserted between existing drives. At this point, ‘mount’ command attempts to mount the newly inserted drives as home.

In such situation, you need to log on as a single user for resolving the problem. However, when you log on, it gives you some error message and in the worst case scenario, you may encounter kernel panic. You can fix this issue using UUID.

UUID creates a unique entry for each hard disk volume in the Linux file system tree. Using UUID offers easy management of your Linux hard disks and creates less complication while adding or removing the disk.

Although, UUID is quite useful and it provides various advanced features, but it also has some faults. Sometimes, you may encounter the below error message when you attempt to access a UUID based Linux hard drive:

“Fsck 1.40.8 (13-Mar-200 fsck.ext3: Unable to resolve ‘UUID=d8533154-cef1-4cce-a823-9f3f74aab65b’”

After the above error message, you can not access the particular hard drive. All the data stored on your hard drive become inaccessible and you come across critical data loss. At this point, Linux Recovery Software come for your rescue.

The applications perform absolute Data Recovery Linux in most of the logical data loss situations, using advanced scanning algorithms. These tools enable you to perform Linux Recovery on your own as they have self-descriptive and simple graphical user interface. With read-only and non-destructive behavior, the applications are completely safe to use.

Stellar Phoenix Linux Data Recovery is the most comprehensive application for perfect recovery of all lost data. The software is compatible with all Linux distributions including SUSE, Debian, Red Hat, and Fedora. It recovers lost data from Ext4, Ext3, Ext2, FAT32, FAT16, and FAT12 file system volumes.

Run this command to see your alias

# alias

OUTPUT :-

alias attrib=’chmod’
alias chdir=’cd’
alias copy=’cp’
alias cp=’cp -i’
alias d=’dir’
alias del=’rm’
alias deltree=’rm -r’
alias dir=’/bin/ls $LS_OPTIONS –format=vertical’
alias edit=’pico’
alias ff=’whereis’
alias l.=’ls -d .* –color=tty’
alias ll=’ls -l –color=tty’
alias ls=’/bin/ls $LS_OPTIONS’
alias mc=’. /usr/share/mc/bin/mc-wrapper.sh’
alias mem=’top’
alias move=’mv’
alias mv=’mv -i’
alias pico=’pico -w -z’
alias rm=’rm -i’
alias search=’grep’
alias v=’vdir’
alias vdir=’/bin/ls $LS_OPTIONS –format=long’
alias which=’type -path’
alias wtf=’watch -n 1 w -hs’
alias wth=’ps -uxa | more’

As you can see, you do have an alias with cp, so how do you overwrite without prompt? what you need to do is remove that cp alias.
using  unalias command you can get rid of the error “cp: overwrite”.

Run this command to remove alias cp,

#unalias cp

so now when you do the alias command, you wont see the cp alias anymore. so what happens if your not the admin or dont have access to root, then you can run an unaliased cp command.

#cp -rf /this/file /to/this/file

hope this help you out.

As the name implies, rescue mode is provided to rescue you from something. During normal operation, your Red Hat Linux system uses files located on your system’s hard drive to do everything — run programs, store your files, and more.

However, there may be times when you are unable to get Linux running completely enough to access its files on your system’s hard drive. Using rescue mode, you can access the files stored on your system’s hard drive, even if you cannot actually run Linux from that hard drive.

Normally, you will need to get into rescue mode for one of two reasons:

• You are unable to boot Linux.
• You are having hardware or software problems, and you want to get a few important files off your system’s hard drive.

Next, we will take a closer look at each of these scenarios.

Unable to Boot Linux

This problem is often caused by the installation of another operating system after you have installed Red Hat Linux. Some other operating systems assume that you have no other operating systems on your computer, and they overwrite the Master Boot Record (MBR) that originally contained the GRUB or LILO boot loader. If the boot loader is overwritten in this manner, you will not be able to boot Red Hat Linux unless you can get into rescue mode.

Another common problem is if you use a partitioning tool to resize a partition or create a new partition from free space after installation and it changes the order of your partitions. If the partition number of your / partition changes, the boot loader will not be able to find it to mount the partition. To fix this problem, boot in rescue mode and modify /boot/grub/grub.conf if you are using GRUB or /etc/lilo.conf if you are using LILO.

Hardware/Software Problems

This category includes a wide variety of different situations. Two examples include failing hard drives and forgetting to run LILO after building a new kernel (if you are using LILO as your boot loader). In both of these situations, you may be unable to boot Red Hat Linux. If you can get into rescue mode, you might be able to resolve the problem or at least get copies of your most important files.

Booting Rescue Mode

To boot your system in rescue mode, boot off of a Red Hat Linux boot disk or Red Hat Linux CD-ROM #1, and enter the following command at the installation boot prompt:

boot: linux rescue

You can get to the installation boot prompt in one of these ways:

• By booting your system from an installation boot diskette made from the boot.img image. This method requires that the Red Hat Linux CD-ROM #1 be inserted as the rescue image or that the rescue image be on the hard drive as an ISO image. [1]
• By booting your system from the Red Hat Linux CD-ROM #1.
• By booting from a network disk made from the bootnet.img or PCMCIA boot disk made from pcmcia.img. You can only do this if your network connection is working. You will need to identify the network host and transfer type. For an explanation of how to specify this information, see Installing over the Network in the Official Red Hat Linux Installation Guide.

After booting off a boot disk or Red Hat Linux CD-ROM #1 and providing a valid rescue image, you will see the following message:

The rescue environment will now attempt to find your Red Hat
Linux installation and mount it under the directory
/mnt/sysimage. You can then make any changes required to your
system. If you want to proceed with this step choose
'Continue'.
If for some reason this process fails you can choose 'Skip' 
and this step will be skipped and you will go directly to a
command shell.

If you select Continue, it will attempt to mount your filesystem under the directory /mnt/sysimage. If it fails to mount a partition, it will notify you. If you select Skip, your filesystem will not be mounted. Choose Skip if you think your filesystem is corrupted.

Once you have your system in rescue mode, a prompt appears on VC (virtual console) 1 and VC 2 (use the [Ctrl]-[Alt]-[F1] key combination to access VC 1 and [Ctrl]-[Alt]-[F2] key combination to access VC 2):

bash#

If you selected Continue to mount your partitions automatically and they were mounted successfully, you are in single-user mode.

To mount a Linux partition manually inside rescue mode, create a directory such as /foo, and type the following command:

mount -t ext3 /dev/hda5 /foo

In the above command, /foo is a directory that you have created and /dev/hda5 is the partition you want to mount. If the partition is of type ext2, replace ext3 with ext2.

If you do not know the names of your partitions, use the following command to list them:

fdisk -l

If your filesystem is mounted and you want to make your system the root partition, use the command chroot /mnt/sysimage. This is useful if you need to run commands such as rpm that require your root partition to be mounted as /. To exit the chroot environment, type exit, and you will return to the bash# prompt.

From the bash# prompt, you can run many useful commands including:

anaconda gzip mkfs.ext2 ps
badblocks head mknod python
bash hwclock mkraid python1.5
cat ifconfig mkswap raidstart
chattr init mlabel raidstop
chmod insmod mmd rcp
chroot less mmount rlogin
clock ln mmove rm
collage loader modprobe rmmod
cp ls mount route
cpio lsattr mpartition rpm
dd lsmod mrd rsh
ddcprobe mattrib mread sed
depmode mbadblocks mren sh
df mcd mshowfat sync 
e2fsck mcopy mt tac
fdisk mdel mtools tail
fsck mdeltree mtype tar
fsck.ext2 mdir mv touch
fsck.ext3 mdu mzip traceroute
ftp mformat open umount
gnome-pty-helper minfo pico uncpio
grep mkdir ping uniq
gunzip mke2fs probe zcat

Booting Single-User Mode Directly

You may be able to boot single-user mode directly. If your system boots, but does not allow you to log in when it has completed booting, try single-user mode.

If you are using GRUB, use the following steps to boot into single-user mode:

1. If you have a GRUB password configured, type p and enter the password.
2. Select Red Hat Linux with the version of the kernel that you wish to boot and type e for edit. You will be presented with a list of items in the configuration file for the title you just selected.
3. Select the line that starts with kernel and type e to edit the line.
4. Go to the end of the line and type single as a separate word (press the [Spacebar] and then type single). Press [Enter] to exit edit mode.
5. Back at the GRUB screen, type b to boot into single user mode.

If you are using LILO, specify one of these options at the LILO boot prompt (if you are using the graphical LILO, you must press [Ctrl]-[x] to exit the graphical screen and go to the boot: prompt):

boot: linux single
boot: linux emergency

In single-user mode, you computer boots to runlevel 1. Your local filesystems will be mounted, but your network will not be activated. You will have a usable system maintenance shell.

In emergency mode, you are booted into the most minimal environment possible. The root filesystem will be mounted read-only and almost nothing will be set up. The main advantage of emergency mode over linux single is that your init files are not loaded. If init is corrupted or not working, you can still mount filesystems to recover data that could be lost during a re-installation.

Have you ever rebuilt a kernel and, eager to try out your new handiwork, rebooted before running /sbin/lilo? If you did not have an entry for an older kernel in lilo.conf, you had a problem. If you would like to know a solution to this problem, read this section.

In many cases, you can boot your Red Hat Linux system from the Red Hat Linux boot disk [1] with your root filesystem mounted and ready to go. Here is how to do it:

Enter the following command at the boot disk’s boot: prompt:

linux single root=/dev/hdXX initrd=

Replace the XX in /dev/hdXX with the appropriate letter and number for your root partition.

What does this command do? First, it starts the boot process in single-user mode, with the root partition set to your root partition. The empty initrd specification bypasses the installation-related image on the boot disk, which will cause you to enter single-user mode immediately.

Is there a negative side to using this technique? Unfortunately, yes. Because the kernel on the Red Hat Linux boot disk only has support for IDE built-in, if your system is SCSI-based, you will not be able to do this. In that case, you will have to access rescue mode using the linux rescue command mentioned above.

dmesg

When I have a problem (or when I am attaching a usb device) one of the first places I go is the dmesg command. The dmesg command prints out the kernel keyring buffer. The information you will get will be all of the information you do not see when your system is booting. This is a great place to get information (low level) on your hardware. On one of my laptops, I run dmesg and near the top I see:

Phoenix BIOS detected: BIOS may corrupt low RAM, working it around.
last_pfn = 0x7f6d0 max_arch_pfn = 0x100000
x86 PAT enabled: cpu 0, old 0x7040600070406, new 0x7010600070106
kernel direct mapping tables up to 38000000 @ 10000-15000
Using x86 segment limits to approximate NX protection
RAMDISK: 37c6a000 - 37fef4a2

From that I can tell I have a Phoenix bios. Pretty obvious. A little later I see:

Security Framework initialized
SELinux:  Initializing.
SELinux:  Starting in permissive mode

Now I know Security Enhanced Linux is starting, in permissive mode, at bootup. And even further on down the line I see:

CPU1: Intel(R) Pentium(R) Dual  CPU  T2390  @ 1.86GHz stepping 0d
checking TSC synchronization [CPU#0 -> CPU#1]: passed.
Brought up 2 CPUs
Total of 2 processors activated (7447.76 BogoMIPS)

The above shows me information about my CPU. Good to know.

The most important information you will probably get from dmesg is the information regarding attached USB devices. When you plug in a USB device you will need to know what special device this is attached to so you can mount it. This will occur at the bottom of the dmesg command output.

The output of dmesg is quite long and will scroll by very quickly. When I run this command I always pipe it through the less command like so:

dmesg | less

This way I can view the output one page at a time.

/var/log

This special directory is the Mac Daddy of information gathering. Fire up a terminal window and issue the command ls /var/log/ and see what it contains. You see, included in this listing, such log files and log directories as:

• boot.log – boot information
• cron – cron logs
• cups – directory of all printing logs
• httpd – Apache logs
• mail – Mail server logs
• maillog – The mail log
• messages – Post-boot kernel information
• secure – Security log
• Xorg.0.log – X Server log

You can see the listing of log files in the /var/log directory, but in order to actually read the log files you have to be the root user (or use sudo).

Viewing with tail

One of the handiest methods of viewing log files is using the tail command. What tail does is follow the running output of a log file. For instance if I want to follow my /var/log/secure log to watch for security issues I would enter the command tail -f /var/log/secure. The f switch tells tail to follow. If  you don’t add the f switch tail will just list the output all at once (as if you just issued less /var/log/secure.)

Final Thougths

There is so much information to be gained from reading log files. The Linux operating system makes reading log files easy, once you know which log file does what. Take a poke around /var/log to find out exactly what you have and where you need to look for the problem you are having.

recently  I experienced with a slow boot issue on my fedora 16 (Verne)

Due to iscsi service , my boot load time takes more than 15 mins, earlier it use to boot in less than 2 mins.

In short, will help to improve boot time…
As long as you do not use iscsi , it can certainly be disabled to speed up boot time.
before we run a command , we can check ourself with chkconfig –list command, to verify the iscsi service, whether its on or not , as follows.

Note: This output shows SysV services only and does not include native
systemd services. SysV configuration data might be overridden by native
systemd configuration.

akmods             0:off    1:off    2:on    3:on    4:on    5:on    6:off
iscsi              0:off    1:off    2:on    3:on    4:on    5:on    6:off
iscsid             0:off    1:off    2:off    3:on    4:on    5:on    6:off
jexec              0:on    1:on    2:on    3:on    4:on    5:on    6:on
livesys            0:off    1:off    2:off    3:on    4:on    5:on    6:off
livesys-late       0:off    1:off    2:off    3:on    4:on    5:on    6:off
named              0:off    1:off    2:off    3:off    4:off    5:off    6:off
netconsole         0:off    1:off    2:off    3:off    4:off    5:off    6:off
netfs              0:off    1:off    2:off    3:on    4:on    5:on    6:off
network            0:off    1:off    2:on    3:on    4:on    5:on    6:off
pcp                0:off    1:off    2:off    3:off    4:off    5:off    6:off
pmie               0:off    1:off    2:off    3:off    4:off    5:off    6:off
pmproxy            0:off    1:off    2:off    3:off    4:off    5:off    6:off
rrdcached          0:off    1:off    2:off    3:off    4:off    5:off    6:off
sandbox            0:off    1:off    2:off    3:off    4:off    5:on    6:off
vnstat             0:off    1:off    2:off    3:off    4:off    5:off    6:off

To disable the isci initiator and daemon you can do the following as root,

That will prevent the daemons from starting on boot and stopping them if they have already started.

To remove it , run as root

# rpm -e kernel-version

in a terminal (Main Menu > System Tools > Terminal) where version is the full release number. Enter

# rpm -q  kernel

to get the installed kernels.

or

Run this command as root/super user,

# package-cleanup –oldkernels

After loading packages you will be promoting to enter an option,as below…

Dependencies Resolved

==============================================================================================
Package                                           Arch                         Version                                        Repository                         Size
==============================================================================================
Removing:
kernel                                            i686                         3.1.5-2.fc16                                   @updates                           92 M
kernel-devel                                      i686                         3.1.5-2.fc16                                   @updates                           26 M
Removing for dependencies:
kmod-wl-3.1.5-2.fc16.i686                         i686                         5.100.82.112-1.fc16.5                          installed                         2.5 M

Transaction Summary
===============================================================================================
Remove        3 Packages

Installed size: 121 M
Is this ok [y/N]: y
Downloading Packages:
Running Transaction Check
Running Transaction Test
Transaction Test Succeeded
Running Transaction
Warning: RPMDB altered outside of yum.
Erasing    : kmod-wl-3.1.5-2.fc16.i686-5.100.82.112-1.fc16.5.i686                                                                                                1/3
Erasing    : kernel-3.1.5-2.fc16.i686                                                                                                                            2/3
Erasing    : kernel-devel-3.1.5-2.fc16.i686                                                                                                                      3/3

Removed:
kernel.i686 0:3.1.5-2.fc16                                                      kernel-devel.i686 0:3.1.5-2.fc16

Dependency Removed:
kmod-wl-3.1.5-2.fc16.i686.i686 0:5.100.82.112-1.fc16.5

Complete!
That’s it. you have removed your old/unused kernels.

First, if you dont have anything critically important on your computer, and you are satisfied with its speed, you dont need raid. If your computer is fast enough but has critical data, and you do backups regularly No.

Here is where it gets tricky: Raid 0 is just striping, it will give you extra speed in the hard drive reads/writes, BUT you lose reliability – there is no redundancy which is fine as long as you have good backups, and backup religiously(as in once a day, every day)!

IF your data is any kind of important, you need to back it up if you want to run Raid 0!

How important is the computer and its information? How critically important is the data? How fast do you need it? If you have a business(or just family data) with critical data on it you may prefer raid 1(duplication of data-high cost, fast read but slower write performance), Raid 1 doubles your HD costs, but increases the computers’ reliability.

Raid 5 is the next cheapest/reliable array, you need at least 3 disks for a Raid 5 array, but 4, or 5 disks are more reliable, but costs much more than just a single drive.

>>       zip – package and compress (archive) files

# zip silence silence.zip

or more concisely

# zip -r silence.zip silence

>> unzip – list, test and extract compressed files in a ZIP archive

To  use unzip to extract all members of the archive letters.zip into the current directory and subdirectories below it, creating any subdirectories as
necessary:

# unzip silence.zip

To extract all members of letters.zip into the current directory only:

# unzip -j silence.zip

mydear friend , hope this link  will be bookmarked by you ;)

Type the following command to find out USB pen partition name:

[root@thiyag]# df
Filesystem     1K-blocks     Used Available Use% Mounted on
rootfs          51606140  6148584  44933428  13% /
devtmpfs          953540        0    953540   0% /dev
tmpfs             961808     1000    960808   1% /dev/shm
tmpfs             961808    40612    921196   5% /run
/dev/sda3       51606140  6148584  44933428  13% /
tmpfs             961808    40612    921196   5% /run
tmpfs             961808        0    961808   0% /sys/fs/cgroup
tmpfs             961808        0    961808   0% /media
/dev/sda5      251747076 83478108 155480900  35% /home
/dev/sda1         495844    78680    391564  17% /boot
/dev/sdb1        7898008        4   7898004   1% /media/2E3E-D0DE

We can use fdisk as well to get to know the USB partition,

[root@thiyag]# fdisk -l

Disk /dev/sda: 320.1 GB, 320072933376 bytes
255 heads, 63 sectors/track, 38913 cylinders, total 625142448 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0x9c68a144

Device Boot      Start         End      Blocks   Id  System
/dev/sda1   *        2048     1026047      512000   83  Linux
/dev/sda2         1026048     8759295     3866624   82  Linux swap / Solaris
/dev/sda3         8759296   113616895    52428800   83  Linux
/dev/sda4       113616896   625142447   255762776    5  Extended
/dev/sda5       113618944   625141759   255761408   83  Linux

Disk /dev/sdb: 8103 MB, 8103395328 bytes
196 heads, 32 sectors/track, 2523 cylinders, total 15826944 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0xc3072e18

Device Boot      Start         End      Blocks   Id  System
/dev/sdb1   *          32    15826943     7913456    7  HPFS/NTFS/exFAT

Once identified the partition name type the following command to format the usb pen in Linux
(caution you must select correct usb partition name, otherwise you will loss all the data on hard disk)

[root@thiyag]# mkfs.vfat /dev/sdb1
mkfs.vfat 3.0.12 (29 Oct 2011)
mkfs.vfat: /dev/sdb1 contains a mounted file system.

here we are getting an error as, “mkfs.vfat: /dev/sdb1 contains a mounted file system.”
So it asking us to unmount before we format the USB
here we go for unmount the mounted usb.

[root@thiyag]# umount /dev/sdb1

We havn’t get any error, so we unmounted it ;)

finally, use the following command to format your pendrive/usb drive.

# mkfs.ext3 /dev/sda1

To format as VFAT/FAT32 file system type the following command:

[root@thiyag]# mkfs.vfat /dev/sdb1
mkfs.vfat 3.0.12 (29 Oct 2011)
[root@thiyag]#

hope it works for you too ! :-)