Today, I had an issue I had seen before, but I can never remember how I fix it. As such, I wanted to document it here. Although rare, periodically an abnormally terminated instance will leave behind a shared memory segment.…
Category: Linux
awk silliness
This one-liner will print every other character in upper case. oracle@emgrid01 ~ >echo “the quick brown fox jumped over the lazy dog” | awk -F “” ‘{for (i=1; i
instr() in awk
If you have a long command line string, as you may find with java processes with a lot of properties, what is below will allow you to print those “columns” with a certain value as delimited by a space in…
Who is the big load on my server?!
What is below will show SQL statements for a given window (the last four days in the example below) that are tightly correlated with load average on a server. In general, a statistical correlation greater than 60 means there is…
Using awk with group by functionality
You can use the following example if you need to total numbers over a group in a given file. We first show our sample file… 14:30:57 oracle@emgrid01 ~ >cat list.txt steve:61 steve:14 becky:57 steve:19 jenna:69 stephen:57 maddie:54 jenna:53 abby:41 jenna:21…
Is memory allocated actually in use?
In an earlier article, we talked about actually initializing memory rather than just allocating it. This post will show how we can look at what is allocated in Linux, as well as when it shows as being in use and…
Huge pages
Huge Pages is a feature available in later Linux kernels that provides two important benefits: 1. Locks the memory available to huge pages, so it cannot be paged to disk 2. Make the TLB (translation lookaside buffer) much smaller on…
Where is my close button?!!
So I just updated to Ubuntu 10.4, and the first thing I noticed is the fact the close/minimize/maximize buttons were switched to the top left hand corner from the right corner. I have no clue why something as standard as…
logrotate configured by mere mortals
This will provide a way to implement log file rotations by a non-privileged users using the standard Linux logrotate infrastructure. For our test case, we set up a log file that looks similar to a “normal” log file we may…
memset example
This is just a quick note so I don’t forget. If you don’t run a memset, the memory will only be allocated, but not shown as being used in the OS. int main() { int i = 1; while(i++ <…