How to check CPU and memory Hardware detials in RHEL system?

Using the bellow command, we can see the Memory and CPU related hardware details

#cat  /proc/meminfo


#cat  /proc/cpuinfo

How to write / setup SCTP client server program in RHEL system?

Setup:

Before run any SCTP application, we need to install SCTP libs from

http://lksctp.sourceforge.net/

Using the below command, register the SCTP module into kernel.

#modprobe sctp

http://linux.about.com/od/commands/l/blcmdl8_modprob.htm

SCTP Application writing:-

SCTP client and server system call follow same as TCP. ( like socket,bind,listen and accept )

Creating SCTP socket

Sock = socket( AF_INET, SOCK_STREAM, IPPROTO_SCTP );

Before listen, we need to set the value for the no.of stream for the socket using setsockopt system call.

struct sctp_initmsg startupsctp;

startupsctp.sinit_num_ostreams = 3;

startupsctp.sinit_max_instreams = 3;

startupsctp.sinit_max_attempts = 4;

ret = setsockopt( listen_Socket, IPPROTO_SCTP, SCTP_INITMSG, & startupsctp, sizeof(startupsctp) );

Using sctp_sendmsg() and sctp_recvmsg() system calls , we can send/receive data over the SCTP socket.

Example code:-

Please refer : http://www.ibm.com/developerworks/linux/library/l-sctp/

How to decompress the tar.bz2 format file?

#tar -xvjf xxxx.tar.bz2
tmp/test.txt

Options:

* x - extract
* c - create to create
* v - verbose
* z - gzip
* j - bzip2 ( .bz2 )
* f - file name ( after the “f” indicate the input/output file name )

IPsec configuration - useful links

IPsec HOWTO : http://www.ipsec-howto.org/t1.html

IPSEC using Linux Kernel 2.6: http://www.shorewall.net/IPSEC-2.6.html

IPsec Host-to-Host Configuration in RHEL:
http://www.redhat.com/docs/manuals/enterprise/RHEL-4-Manual/security-guide/s1-ipsec-host2host.html

How to prepare ISO image and test it?

An ISO image is an archive file/disc image of an optical disc in a format defined by the International Organization for Standardization (ISO). ISO image files typically have a file extension of .iso

Create folder name with "cd"

#mkdir cd
#cd cd

copy your application/package/rpm/script file into the folder
#cp /root/test/Add-lnx26.sh .
#ls
Add-lnx26.sh

run the below command for creating the iso image with the name of add.iso

#cd ..

#mkisofs -l -r -N -d -D -J -o add.iso -V "Add-1.0" -A "Add program for ISO image test" cd

Warning: creating filesystem that does not conform to ISO-9660.
Total translation table size: 0
Total rockridge attributes bytes: 247
Total directory bytes: 0
Path table size(bytes): 10
Max brk space used c000
182 extents written (0 MB)

#ls
cd add.iso

How to find the particular package installed or not?

Using “rpm –qa ” command, we can find whether the package installed or not.

Below shell script use the command for determine the given string/name package rpm installed or not installed.

############

rpmcheck.sh

############

#!/bin/bash
rpm -qa "*$1*" > r1
line_no=$( wc -l < r1 )
echo "$line_no"
if [ $line_no == 0 ]
then
echo "rpm not installed "
else
echo "rpm installed "
fi


Output:

[root@home linux]# ./rpmcheck.sh milton
0
rpm not installed
[root@home linux]# ./rpmcheck.sh boost
2
rpm installed

How to find which rpm (package) install the particular file?

Using “rpm –qf” command, we can find the rpm package name for the lib file.

Example:

[root@home linux]# rpm -qf /usr/lib/libpython2.3.so
python-2.3.4-14.1

[root@home linux]# rpm -qf /usr/include/boost/blank.hpp
boost-devel-1.32.0-1.rhel4