Masquerading send your mail with valid domain name, not with your hostname
like valid doamin raman@mydoamin.com not raman@inf1sysadm1.ind.bond.com

I am going to share my configuration.

Open your sendmail.mc ( /etc/mail/sendmail.mc)

FEATURE(`accept_unresolvable_domains')dnl
FEATURE(`domaintable')dnl
FEATURE(`relay_based_on_MX')dnl
LOCAL_DOMAIN(`localhost.localdomain')dnl
MASQUERADE_AS(`mydomain.com')dnl
FEATURE(masquerade_envelope)dnl
FEATURE(masquerade_entire_domain)dnl
FEATURE(allmasquerade)
MASQUERADE_DOMAIN(mydomain.com)dnl


After that

#echo inf1sysadm1.ind.my.com mydomain.com >> /etc/mail/domaintable"


Then run m4 & restart sendmail services.

## m4 /etc/mail/sendmail.mc > /etc/mail/sendmail.cf

# /etc/init.d/sendmail restart

Through telnet you can check your setting.

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multiple lines edit by Sed command.

Suppose you have a file with 1000000 lines.. & you want to change any word. Use sed command.

For example: i have a file with name rk.conf with 80000 lines & in this file,want to change lib word with lib64. i use sed this command & my problem RESOLVED.

Command like this.

#sed -i 's/lib/lib64/g' rk.conf

Enjoy... hope this will save your time........

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Sendmail (host map: lookup (domain.com): deferred

If you get this error... on sendmail.

[root@Test_Srv ~]# mailq
/var/spool/mqueue (9 requests)
-----Q-ID----- --Size-- -----Q-Time----- ------------Sender/Recipient-----------
o1RKaZr6018628 10 Wed Feb 10 21:37 abc@abc.com
(host map: lookup (abc.com): deferred)




Solution:-

Check your DNS resoulation.

Try to nslookup on domain or dig.

[root@inf1sysadm1 ~]# dig abc.com

; <<>> DiG 9.6.1-P2-RedHat-9.6.1-7.P2.fc11 <<>> abc.com
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 7633
;; flags: qr rd ra; QUERY: 1, ANSWER: 1, AUTHORITY: 3, ADDITIONAL: 3


Domain name must be resolve.

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Chkconfig command

# chkconfig --list
With this command, you will see a list of system services and whether they are started (on) or stopped (off) in runlevels 0-6

To check a particular service .. in my example sendmail

root@inf1sysadm1 ~]# chkconfig --list sendmail
sendmail 0:off 1:off 2:on 3:on 4:off 5:on 6:off

#chkconfig 235 on

If you found any serivce run in run level 4,6 as well... use following command to stop.
In my example only run in 4th run level.

[root@inf1sysadm1 ~]# chkconfig --list | grep sendmail
sendmail 0:off 1:off 2:on 3:on 4:on 5:on 6:off

[root@inf1sysadm1 ~]# chkconfig --level 4 sendmail off

[root@inf1sysadm1 ~]# chkconfig --list | grep sendmail
sendmail 0:off 1:off 2:on 3:on 4:off 5:on 6:off

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Xen disk image resizing.

In My Setup....
To resize 4Gb img ( xen virtual machine) to 9Gb
Following steps perform by me & working fine. going to share with you.

1) xm list ( show current running VM)

2) xm shutdown sgd1mon1 ( to shutdown the machine)

3) For safer side .. i take the backup.
[root@sgd1vmbe09 ~]# cd /var/lib/xen/images/
#cp -a sgd1mon1.img sgd1mon1.img.bak
4) verify MD5 Sum
# md5sum sgd1mon1.img
8dfb611eacd0aa7291d1737967845688 sgd1mon1.img
# md5sum sgd1mon1.img.bak
8dfb611eacd0aa7291d1737967845688 sgd1mon1.img.bak

5) Created 5Gb temp file
[root@sgd1vmbe09 images]# dd if=/dev/zero of=tempfile bs=1024 count=5000000
5000000+0 records in
5000000+0 records out
5120000000 bytes (5.1 GB) copied, 77.1266 seconds, 66.4 MB/s

6) Appending the existing image.
[root@sgd1vmbe09 images]# cat tempfile >> sgd1mon1.img

7) Resize the space

[root@sgd1vmbe09 images]# resize2fs -f sgd1mon1.img

8) check a Linux ext2/ext3 file system
[root@sgd1vmbe09 images]# fsck.ext3 sgd1mon1.img

9) Finally start the VM
[root@sgd1vmbe09 images]# xm create sgd1mon1
Using config file "/etc/xen/sgd1mon1".
Started domain sgd1mon1

10) Login and check the partition table.
[root@sgd1mon1 ~]# fdisk -l

Disk /dev/xvda: 9314 MB, 9314304000 bytes
255 heads, 63 sectors/track, 1132 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes


Next part extend the machine LVM.... :)

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