Whenever I am writing a script in perl or bash, I always wish that there
was some way to have all the commands logged or output to screen. I know
there is “set -x” option to have debugging enabled, but sometimes that
seems to be too much information and I dont really need all that. So, here
is something I found recently for bash to log all the executed commands.
Generally quite a lot of us would have used the script command. This generates the logs for the session. But the problem with the logs is that it contains a lot of un-readable characters. These characters are mostly from the color codes, and as such can be removed very easily with a single command:
cat typescript | perl -pe 's/e([^[]]|[.*.*?[a-zA-Z]|].*?a)//g' | col -b > typescript-processed
This assumes the input log file is named as typescript and the output is kept as typescript-processed. You can change the names as required.
Continue readingTo create simple text tables to paste in emails or to use in any other document where you want to show a table, here is something that you can use. There is a perl module which provides “tablify“. And here is how to use it:
sudo yum install perl-Text-RecordParser
This will install a command “tablify” that you can use in number of ways. Here is a simple example to use it. You can read the man pages to see how you can use it.
Continue readingIf you have got this question in your mind, then you are in right place.
vim -V20 2>&1 |tee
You can give the debugfile as any file, where you would want to log the debug messages. This will log a lot of information in the debugfile, you can open the file, once you have got the error in the main vim window. After this, you can open the debugfile and simply search for the error that you were getting. Just look for the reason why this error is originated in the debug logs and then it should be pretty simple to fix that.
Continue readingHere is a short description of pigz:
pigz, which stands for parallel implementation of gzip,
is a fully functional replacement for gzip that exploits
multiple processors and multiple cores to the hilt when compressing data.
And for the installation:
sudo yum install pigz
With pigz, if you don’t have many things running on your multi processor machine then you will see a significant improvement when you are gzipping the files.
Continue reading
Here is a nice link on BASH History Expansion. There are lot of examples in this page and some of them might be quite useful. But here are my list of favourites:
!!
This is probably the most used one by me. This will repeat the last command. And this works even in conjunction with other commands like
Continue readingHere are one sql script that I found some time back. This will be listing the top 5 SQL queries in Oracle.
SET linesize 300
SET PAGESIZE 200
select *
from
(select sql_text,
sql_id,
elapsed_time,
cpu_time,
user_io_wait_time
from sys.v_$sqlarea
order by 5 desc)
where rownum < 6;
quit;
