Quick tip to find out the clients connecting to a NFS server.
- Check the ports that NFS uses
[code] grep -i nfs /etc/services [/code]
- Check the clients connecting to the server using the port from above
[code] netstat -an | grep 2049 [/code]
Uncategorized
HOW TO : Search ownership of files in Linux
Say you have a directory with a bunch of sub directories and files and you want to see if all the files are owned by a particular user, you can use the following set of commands
[code]ls DIRECTORY_PATH -l -R | awk {‘print $3’} | grep -v USER_NAME[/code]
The set of commands do the following
- ls -l -R shows the list of files and directories
- awk prints the name of the owner of the file (it is the third column)
- grep shows only the lines where the owner name doesn’t match
And yeah.. this works in most variants of Linux :).
Unimaginative Error Pages : HP.com
One of the largest tech company in the world
Supposedly earns billions in consulting services
and what happens when thousands (and let’s imagine millions) hit their web app store?
Overheard : Comment about complex organizational structures
More tiers means more tears..
Keep it simple :).
HOW TO : Apache and SELinux
Quick note for future reference..
If you ever run into errors like this
[code]
<pre>Starting httpd: Warning: DocumentRoot [/var/www/html/static] does not exist
Warning: DocumentRoot [/var/www/html/static] does not exist
Warning: DocumentRoot [/var/www/html/static] does not exist
Warning: DocumentRoot [/var/www/html/static] does not exist
(13)Permission denied: httpd: could not open error log file /etc/httpd/logs/error_log.
Unable to open logs
[FAILED]
[/code]
And you are scratching your head why Apache is throwing these errors, even when the said directory and files exist. And you have the right permissions!! Check if you have SELinux running and being enforced.
On RHEL, you can check if SELinux is running by
[code]cat /selinux/enforce [/code]
The two values are 0 and 1. 0 means, SELinux is not being enforced and 1 means it is.
You can quickly disable SELinux temporarily by
[code]echo 0 >/selinux/enforce [/code]
If you want to disable it permanently (i.e. survive reboots), you have to edit the file /etc/selinux/config and change the SELINUX line from enabled to disabled.
HOW TO : Playbook for creating an effective IT team
Tom Limoncelli put together a list of questions that are essentially a cheat-sheet to creating and running a very effective IT team. He called it the Limoncelli Test (as a tribute to the Joel Spolsky‘s Joel Test) and it can be found at http://everythingsysadmin.com/the-test.html.
The only additional thing I would add to the list is to have a roadmap for the function you provide and ensure it is updated quarterly. A lot of teams spend a lot of time on what they do now, but don’t focus on what they “can” do. This is similar to IT functions spending more than 70% – 80% of their budgets on maintenance rather than innovating.
Overheard : Random comments about technology
Here are some interesting titbits from a executive summary event hosted by Redhat/Intel that I attended yesterday.
We decreased the execution times for our orders from 1.5 seconds to 5 milliseconds
This from an executive managing the technology organization for a large trading company. Imagine the geekiness in accomplishing this :).
For every 450 smartphones that get activated a server is added to support them
This from an Intel executive. So if there are 500000 android phones being activated every day.. that’s around 1111 servers being added just to serve the android fans :).
1 in 4 servers currently runs Linux
This from a Redhat executive. If anyone doubts that Linux is mainstream.. they are living under a rock 🙂
HOW TO : Use grep to search for credit card numbers
I was looking for a quick way to search for credit card numbers in a file and ran across this excellent post by Adrian Rollett. I tweaked his suggestion a bit to show some additional data.
Original suggestion
[code] grep ‘\(^\|[^0-9]\)\{1\}\([345]\{1\}[0-9]\{3\}\|6011\)\{1\}[-]\?[0-9]\{4\}[-]\?\[0-9]\{2\}[-]\?[0-9]\{2\}-\?[0-9]\{1,4\}\($\|[^0-9]\)\{1\}’ FILE_TO_SEARCH [/code]
My modification
[code]Â grep ‘\([345]\{1\}[0-9]\{3\}\|6011\)\{1\}[ -]\?[0-9]\{4\}[ -]\?[0-9]\{2\}[-]\?[0-9]\{2\}[ -]\?[0-9]\{1,4\}’ –color -H -n FILE_TO_SEARCH [/code]
The modified command will show the name of the file the number was found and at which line. You can tweak it further using additional options for grep. A good reference guide can be found here.
