eztemplate 0.3.0

from PyPI into a virtualenv (recommended)

With virtualenv you create a separate python environment without affecting the rest of your system, therefore this approach is recommended for playing around.

$ sudo apt-get install virtualenv

$ sudo yum install python-virtualenv

$ virtualenv myvenv                # create a new environment in a subdirectory
$ . myvenv/bin/activate            # switch to virtualenv (important)
$ pip install eztemplate           # install eztemplate from PyPI
$ eztemplate --version             # check if the correct version was installed

$ . myvenv/bin/activate            # switch to virtualenv (if not there already)
$ pip install --upgrade eztemplate # upgrade eztemplate from PyPI
$ eztemplate --version             # check if the corrent version was installed

from a git repository into a virtualenv

This is a good approach if you work on the repository and want to test the changes.

$ git clone https://github.com/blubberdiblub/eztemplate.git
$ cd eztemplate                    # change into the cloned repository
$ virtualenv venv                  # create a new environment in a subdirectory
$ . venv/bin/activate              # switch to virtualenv (important)
$ pip install .                    # just specify the directory to install from
$ eztemplate --version             # check if the correct version was installed

$ git pull                         # pull latest commits from remote repository
$ . venv/bin/activate              # switch to virtualenv (if not there already)
$ pip install --upgrade --force-reinstall . # force upgrade eztemplate
$ eztemplate --version             # check if the correct version was installed

from PyPI as system command

$ pip install eztemplate           # install eztemplate from PyPI
$ eztemplate --version             # check if the correct version was installed

$ pip install --upgrade eztemplate # upgrade eztemplate from PyPI
$ eztemplate --version             # check if the corrent version was installed

Getting quick help

Use the help option:

$ eztemplate --help

You can also call the package explictly with Python (and thereby choose which Python installation to use):

$ python -m eztemplate --help

Running without arguments

When you run eztemplate without arguments, it will expect a template on standard input, possibly waiting forever:

$ eztemplate
Hello, world!
<Ctrl-D>
Hello, world!
$

On __*ix__ terminals you can manually cause an end of file by pressing Ctrl-D.

Quick demonstration

You can check that substitution is working by piping a template into the program and specifying a name-value pair (make sure to protect the string with single quotes, otherwise the shell believes you want to substitute a shell variable, replacing it by an empty string):

$ echo 'Hello, $entity.' | eztemplate entity=world
Hello, world.
$

When you’re calling eztemplate from a script or similar - i. e. non-interactively - you should specify everything as explicitly as possible (in particular all input files or stdin as well as name-value pairs) and refrain from using positional arguments. Everything can be specified using options, which avoids ambiguities:

$ echo 'Hello, $entity.' | eztemplate --stdin --arg entity=world
Hello, world.
$

string.Template engine

This engine is named after the string.Template class in the Python standard library. It substitutes identifiers beginning with a dollar sign. To resolve ambiguities, you can also enclose the identifier in curly braces. It’s similar to shell variable subsitution minus the more sophisticated features. It suffices for simple cases where you just need to insert some values into a text:

$ eztemplate --stdin \
>   --arg user="$( getent passwd "$USER" | cut -d: -f5 | cut -d, -f1 )" \
>   --arg food=cake --arg vendor=cafeteria --arg price="$RANDOM" \
>   <<\EOF
> Hello, $user.
>
> If you're hungry, get some ${food}s from the $vendor.
> They're only $$$price per piece.
> EOF
Hello, Niels Boehm.

If you're hungry, get some cakes from the cafeteria.
They're only $29993 per piece.
$