gkirok: centos

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воскресенье, апреля 21, 2013

Linux: "Give root password for maintenance"

source: Linux: "Give root password for maintenance"

In the event your Linux box experiences disk or file system issues you may receive a "Give root password for maintenance" prompt upon reboot. If you have your root password you can login but in the event your using 'slide' or 'sudo' for wheel access or you've just mis-placed your root password - you'll need to reset it.

To reset your root password:

1. When the GRUB loader shows during boot press the spare bar to pause boot.

2. Select your boot kernel.

3. Type 'e' to edit the default kernel line.

4. Type 'e' again on the line that starts with 'kernel'.

5. Add 'init=/bin/bash' to the end of the 'kernel' line then press enter.

6. Type 'b' to boot the modified kernel parameters.

7. Once you're at the /bin/bash prompt you will need to remount the root file system as read/write in order to edit the passwd file:

# mount -o remount,rw /

8. Change your root password:

# passwd root

9. Remount the filesystem back to read only:

# mount -o remount,ro /

10. Reboot your server using CTR-ALT-DELETE.

11. You will now be able to login with your new root password and carry out the maintenance.

вторник, июня 19, 2012

Memcacheq init.d script

source: memcacheq by Alexander Titov (qik)
I removed few parameters from line 43

vim /etc/init.d/memcacheq

#! /bin/sh
#
# chkconfig: - 55 45
# description:  The memcacheq daemon is a network memory cache service.
# processname: memcacheq
# config: /etc/sysconfig/memcacheq
# pidfile: /var/run/memcached/memcacheq.pid

# Standard LSB functions
#. /lib/lsb/init-functions

# Source function library.
. /etc/init.d/functions

if [ -f /etc/sysconfig/memcacheq ];then
        . /etc/sysconfig/memcacheq
fi

# Check that networking is up.
. /etc/sysconfig/network

if [ "$NETWORKING" = "no" ]
then
        exit 0
fi

RETVAL=0
prog="memcacheq"

start () {
        echo -n $"Starting $prog: "

    if [ ! -e /var/run/memcacheq ]; then
        mkdir /var/run/memcacheq
    fi

        # insure that /var/run/memcacheq has proper permissions
    if [ "`stat -c %U /var/run/memcacheq`" != "$USER" ]; then
        chown $USER /var/run/memcacheq
    fi

        daemon --pidfile /var/run/memcacheq/memcacheq.pid /usr/local/bin/memcacheq -d -N -p $PORT -u $USER  -H "$DATADIR" -B $MAXMESSAGE -L $LOGBUF -P /var/run/memcacheq/memcacheq.pid $OPTIONS
#        daemon --pidfile /var/run/memcacheq/memcacheq.pid /usr/local/bin/memcacheq -d -N -p $PORT -u $USER  -m $CACHESIZE -c $MAXCONN -H "$DATADIR" -B $MAXMESSAGE -A $PAGESIZE -L $LOGBUF -P /var/run/memcacheq/memcacheq.pid $OPTIONS
        RETVAL=$?
        echo
        [ $RETVAL -eq 0 ] && touch /var/lock/subsys/memcacheq
}
stop () {
        echo -n $"Stopping $prog: "
        killproc -p /var/run/memcacheq/memcacheq.pid /usr/local/bin/memcacheq
        RETVAL=$?
        echo
        if [ $RETVAL -eq 0 ] ; then
            rm -f /var/lock/subsys/memcacheq
            rm -f /var/run/memcacheq.pid
        fi
}

restart () {
        stop
        start
}


# See how we were called.
case "$1" in
  start)
        start
        ;;
  stop)
        stop
        ;;
  status)
        status memcacheq
        ;;
  restart|reload|force-reload)
        restart
        ;;
  condrestart)
        [ -f /var/lock/subsys/memcacheq ] && restart || :
        ;;
  *)
        echo $"Usage: $0 {start|stop|status|restart|reload|force-reload|condrestart}"
        exit 1
esac

exit $?

vim /etc/sysconfig/memcacheq

# Configuration file for the memcacheq service.

DATADIR=/data1/memcacheq

LOGBUF=1024

MAXMESSAGE=1024

OPTIONS='> /data1/mq_error.log'

USER=root

PORT=22201

service memcacheq start
chkconfig memcacheq on

понедельник, июня 18, 2012

Create partition table and format disk (Centos 6) Softlayer

At SoftLayer i created server with two hard disks: primary (you can choose size max 100GB) and secondary (you can choose size max 300GB)

df doesn't show the secondary disk, you need to create partition, format and mount disk first

[root@server me]# df
Filesystem           1K-blocks      Used Available Use% Mounted on
/dev/xvda2           103108896 91059600   6811588 94% /
tmpfs                  1987292         0   1987292   0% /dev/shm
/dev/xvda1               99150     49491     44539 53% /boot

to see all disks run fdisk

[root@server me]# fdisk -l

Disk /dev/xvdb: 2147 MB, 2147483648 bytes
255 heads, 63 sectors/track, 261 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0x00025cdb

    Device Boot      Start         End      Blocks   Id System
/dev/xvdb1               1         261     2096451   82 Linux swap / Solaris

Disk /dev/xvdc: 322.1 GB, 322122547200 bytes
255 heads, 63 sectors/track, 39162 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0x00000000

Disk /dev/xvdc doesn't contain a valid partition table

Disk /dev/xvda: 107.4 GB, 107374182400 bytes
255 heads, 63 sectors/track, 13054 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0x00000cb5

    Device Boot      Start         End      Blocks   Id System
/dev/xvda1   *           1          13      102400   83 Linux
Partition 1 does not end on cylinder boundary.
/dev/xvda2              13       13055   104754176   83 Linux

primary disk is /dev/xvda, and secondary is /dev/xvdc

run parted to create partition table, run mkfs to format

you will get into parted shell, run mklabel to set disk label (msdos for linux)

[root@server me]# parted /dev/xvdc mklabel msdos
Warning: The existing disk label on /dev/xvdc will be destroyed and all data on this disk will be lost. Do you want to continue?
Yes/No? Yes
Information: You may need to update /etc/fstab.

run mkpart to create partition start from position 0 until end of disk -1, for ext3 filesystem

[root@server me]# parted /dev/xvdc mkpart
Partition type? primary/extended? primary
File system type? [ext2]? ext3
Start? 0
End? -1
Warning: The resulting partition is not properly aligned for best performance.
Ignore/Cancel? Ignore
Information: You may need to update /etc/fstab.

run fdisk to see partition num, now we see all disk normal at fdisk, but df still doesn't show secondary disk

[root@server me]# fdisk -l

Disk /dev/xvdb: 2147 MB, 2147483648 bytes
255 heads, 63 sectors/track, 261 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0x00025cdb

    Device Boot      Start         End      Blocks   Id System
/dev/xvdb1               1         261     2096451   82 Linux swap / Solaris

Disk /dev/xvdc: 322.1 GB, 322122547200 bytes
255 heads, 63 sectors/track, 39162 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0x0003cf5d

    Device Boot      Start         End      Blocks   Id System
/dev/xvdc1               1       39163   314571823+ 83 Linux

Disk /dev/xvda: 107.4 GB, 107374182400 bytes
255 heads, 63 sectors/track, 13054 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0x00000cb5

    Device Boot      Start         End      Blocks   Id System
/dev/xvda1   *           1          13      102400   83 Linux
Partition 1 does not end on cylinder boundary.
/dev/xvda2              13       13055   104754176   83 Linux

[root@server me]# df
Filesystem           1K-blocks      Used Available Use% Mounted on
/dev/xvda2           103108896 91019892   6851296 93% /
tmpfs                  1987292         0   1987292   0% /dev/shm
/dev/xvda1               99150     49491     44539 53% /boot

format partition xvdc1 by mkfs

[root@server me]# mkfs.ext3 /dev/xvdc1
mke2fs 1.41.12 (17-May-2010)
Filesystem label=
OS type: Linux
Block size=4096 (log=2)
Fragment size=4096 (log=2)
Stride=0 blocks, Stripe width=0 blocks
19660800 inodes, 78642955 blocks
3932147 blocks (5.00%) reserved for the super user
First data block=0
Maximum filesystem blocks=4294967296
2400 block groups
32768 blocks per group, 32768 fragments per group
8192 inodes per group
Superblock backups stored on blocks:
32768, 98304, 163840, 229376, 294912, 819200, 884736, 1605632, 2654208,
4096000, 7962624, 11239424, 20480000, 23887872, 71663616

Writing inode tables: done
Creating journal (32768 blocks): done
Writing superblocks and filesystem accounting information: done

This filesystem will be automatically checked every 30 mounts or
180 days, whichever comes first. Use tune2fs -c or -i to override.

mount disk

[root@server me]# mkdir /mnt/xvdc1
[root@server me]# mount /dev/xvdc1 /mnt/xvdc1

add mounted disk to fstab

[root@server me]# vim /etc/fstab

....

/dev/xvdc1 /mnt/xvdc1 ext3 defaults 0 0

check

[root@server me]# df
Filesystem           1K-blocks      Used Available Use% Mounted on
/dev/xvda2           103108896 63571080 34300108 65% /
tmpfs                  1987292         0   1987292   0% /dev/shm
/dev/xvda1               99150     49491     44539 53% /boot
/dev/xvdc1           309636140    195548 293712004   1% /mnt/xvdc1

Полезно: Шифрование флешки в Linux

среда, июня 13, 2012

Mount additional disk to VirtualBox image (centos 6)

shut down you virtual machine
open VirtualBox Manager

choose you machine
click Settings->Storage->SATA Contoller->icon Add Hard Disk
click "Create new disk"
choose format VMDK (Virtual Machine Disk) for example -> next
choose Dynamically allocated for example -> next
enter name, and choose size
click Create
click Ok

run virtual machine
> sudo fdisk -l

Disk /dev/sda: 5475 MB, 5475663872 bytes
4 heads, 32 sectors/track, 83552 cylinders
Units = cylinders of 128 * 512 = 65536 bytes

   Device Boot      Start         End      Blocks   Id System
/dev/sda1               1       78125     4999984   83 Linux
/dev/sda2           78126       79681       99584   83 Linux

Disk /dev/sdb: 107.3 GB, 107374182400 bytes
255 heads, 63 sectors/track, 13054 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes

Disk /dev/sdb doesn't contain a valid partition table
- I added 100Gb disk that got name /dev/sdb
- "Disk /dev/sdb doesn't contain a valid partition table" mean that you need to format this disk first
> mkdir /mnt/mydisk
> mount -t ext3 /dev/sdb1 /mnt/mydisk
> cd /mnt/mydisk
> df
to mount automatically on boot, add disk to /etc/fstab my /etc/fstb for example, i added last line

LABEL=79d3d2d4 / ext4    defaults,noatime 0 0
LABEL=e21a3e10 /boot ext3    defaults,noatime 0 0
devpts     /dev/pts devpts gid=5,mode=620   0 0
tmpfs      /dev/shm tmpfs   defaults         0 0
proc       /proc     proc    defaults         0 0
sysfs      /sys      sysfs   defaults         0 0
/dev/sdb1   /mnt/mydisk ext3 defaults      0 0

DONE

gkirok