Thursday, September 29, 2011

Replacing space with newline

There are a few ways to achieve that:

1. sed

$ echo "one two three" | sed 's/ /\n/g'
2. awk
$ echo "one two three" | awk '$1=$1' RS= OFS="\n"
3. tr
$ echo "one two three" | tr -s ' ' '\n'
3 ways to do it, have fun

Tuesday, September 27, 2011

Multiple sed expression in one line

To do multiple sed expression in one line, you can use -e a few times according to your need. For example:

To subtitute 'little' with 'big' and 'lamb' with 'cow' in "Mary had a little lamb" we can use:

$ echo 'Mary had a little lamb' | sed -e 's/little/big/' -e 's/lamb/cow/'
Mary had a big cow
where -e is for expression flag, 's/little/big/' is the first expression and 's/lamb/cow/' is the second expression

That's all.

Friday, September 23, 2011

Simple http server using python

This tip is really useful when you need a really quick web server running without too much hassle. Python comes with http server built-in that you can activate in a matter of seconds if you have python already installed. If you haven't install it, you might need an additional few minutes to install it. Below are the steps (this is assuming you are using redhat/fedora linux):

1. open a terminal and install python

# yum install python
2. Once done, browse to any directory that you want to be your document root directory, in this example I'll use /home/myuser
# cd /home/myuser
3. Run the below command to start the simple http server, where 8000 is the port number the server will use
# python -m SimpleHTTPServer 8000
Serving HTTP on port 8000 ...
4. Now open a browser, and type to access the server, where is your machine's ip address