In last months reader poll I asked about Firewall on dedicated UNIX / Linux box.
Do we really need a firewall?
Personally, I install firewall on all boxes to filter out unwanted junk and IPs; even if box is only running public service such as a web server. The overall idea is to limit access and reduce liability on my part if serer got rooted (read as compromised). Remember, bad boys never play by the rules.
Usually you run mysqldump to create a database copy and backups as follows:
Common Unix Printing System (CUPS) is a modular computer printing system for Apple OS X, Linux and UNIX like operating systems. It allows Linux computer to act as a printer server. As a server it accepts printing requests from all client computer and send them to actual printer. It does printing accounting and other important stuff.
dd is a perfect tool for copy a file, converting and formatting according to the operands. dd command works on Linux and a Unix-like system whose primary job is to convert and copy files. It can create exact CD-ROM ISO image or create a new CD/DVD iso image. This is useful for making a backup, as well as for hard drive installations, require a working the use of ISO images.
One of my friend installed Oracle first time. After installation, he just wants to make sure everything is working fine so he called me. If you are installing oracle for Unix/Linux oses first time then it will confuse you. He wanted to know how to start oracle service and test it. He emailed me the following error:
ORA-27101: shared memory realm does not exist
ORA-01034: ORACLE not available
You need to add following line to oracle userâ€™s .bash_profile file for testing purpose (once it is tested, you can give control to Oracle DBA) (login as a oracle user):
$ cd;vi .bash_profile
Append following lines:
Save file. Just load the above settings:
$ . .bash_profile
Start oracle Net listing service:
$ lsnrctl start
ALTERNATIVELY use full path:
$ /home/oracle/oracle/product/10.2.0/db_1/bin/lsnrctl start
Start oracle database:
ALTERNATIVELY, use full path:
Connect to Oracle database with sqlplus client (test it with scott username):
$ sqlplus "scott/tiger"
sql> select * from tab;
To shutdown Oracle database:
$ lsnrctl stop
If you are new to Oracle try out Oracle Database 10g Documentation library, especially 2 Day DBA is fantastic document. Do not forget check out John Smiley’s “Installing Oracle Database 10g Release 2 on Linux x86” article. It will teach you the basics of installing Oracle Database 10g Release 2 on Red Hat Enterprise Linux or Novell SUSE Enterprise Linux, from the bare metal up.
Reading an IP address in shell script required many time. However, different Linux distribution stores IP address in different files. If you are looking to run script under different UNIX like OSes such as Solaris or FreeBSD then you need to use the ifconfig command. The ifconfig command is not just used to configure a network interface, but it can be use to obtained information such as network IP, netmask and much more.
The replace command is a string-replacement utility. It changes strings in place in files or on the standard input. This command uses a finite state machine to match longer strings first. It can be used to swap strings. This command is similar to the Perl -pie syntax or sed (stream editor) command.