Posts Tagged ‘shell’

Python from command line

September 18, 2013 Leave a comment

You want to calculate something with Python quickly, from the command line. You might even want to use Python in a bash script to produce some result.


$ python -c "print 2*3"

Storing the result in a variable:

$ X=`python -c "print 2*3"`
$ echo $X

Thanks to Tajti A. for the tip.

Update (20170803)
You can also pass a bash variable to the embedded Python:

VAL="cat dog cat"                                                                                                                                                                             
NEW=`python3 -c "print('$VAL'.replace('dog', 'wolf'))"`                                                                                                                                       
echo $NEW

Output: “cat wolf cat”.

Categories: python Tags: , , ,

call python in a shell script

March 5, 2012 Leave a comment

Floating point arithmetic in bash is problematic, expr supports integers only for instance.

Not an optimal solution but it works:

$ python -c "print 5.5*3"

$ num=`python -c "print 5.5*3"`
$ echo $num
Categories: python Tags: ,

IPython, an enhanced Python shell

March 19, 2011 Leave a comment

IPython is an interactive shell for the Python programming language that offers enhanced introspection, additional shell syntax, syntax highlighting, tab completion and rich history. It is a component of the SciPy package.” (source)


In the book Python for Unix and Linux System Administration, there is a long chapter (Ch. 2) dedicated to IPython!

Installation and usage
Install it via apt-get:

sudo apt-get install ipython

I made the alias “ip” for the command “ipython”. Note that there is a command “ip” for manipulating routing and tunnels that the alias will hide, but it’s not likely I’ll ever use that command.

alias ip='ipython'

The config file of IPython is located at ~/.ipython/

Categories: python Tags: , ,