Created
August 14, 2014 23:22
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A little trick to embed python code in a BASH script.
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| #!/bin/bash | |
| # Here are some embedded Python examples using Python3. | |
| # They are put into functions for separation and clarity. | |
| # Simple usage, only using python to print the date. | |
| # This is not really a good example, because the `date` | |
| # command works just as well. | |
| function date_time { | |
| python3 - <<END | |
| from datetime import datetime | |
| print('Current date:') | |
| print(datetime.now()) | |
| END | |
| } | |
| # Call the python code. | |
| date_time | |
| # Sending a variable to Python from BASH | |
| function env_args { | |
| # Put an environment arg into Python. | |
| # Must be on the same line as the command. | |
| TESTARG="My Value" python3 - <<END | |
| from os import environ | |
| print('Your environment arg: {}'.format(environ.get('TESTARG', 'missing!'))) | |
| END | |
| } | |
| env_args | |
| # Retrieve output from Python and put it into a BASH variable. | |
| # This uses a subshell to retrieve whatever python prints out. | |
| function val_from_python { | |
| # Get a python value from BASH. | |
| pythonval="$(python3 - <<END | |
| import os | |
| print('cwd: {}'.format(os.getcwd())) | |
| END | |
| )" | |
| echo "Python value is: $pythonval" | |
| } | |
| val_from_python | |
| # You can put small python snippets directly into your shell files. | |
| # Here's an example using `urllib` to download some html, and then | |
| # using it in BASH. | |
| # (granted that you could do this in Python itself, | |
| # or you could write it all in BASH, but this is just an example.) | |
| function python_power { | |
| # Grab the html from python.org's PEP8 page and save it to a bash variable. | |
| # On error, the output will be a basic HTML page with the error message. | |
| local pythonval="$(python3 - <<END | |
| from urllib import request | |
| try: | |
| resp = request.urlopen('http://legacy.python.org/dev/peps/pep-0008/') | |
| data = resp.read().decode('utf-8') | |
| print(data) | |
| except Exception as ex: | |
| print(""" | |
| <html>\n<head>\n<title>Error in python_power</title>\n</head>\n | |
| <body>\nThere was an error retrieving that page: {}\n</body> | |
| """.format(ex)) | |
| END | |
| )" | |
| # Print the content so it can be used by other commands. | |
| # (you also could've saved it to a global variable.) | |
| echo $pythonval | |
| } | |
| # Direct the output of this python function to a file. | |
| # The html will not be styled correctly, because no css files are downloaded. | |
| # But the point here is that you can have the full power of python without | |
| # writing separate scripts. Small python snippets can be embedded and used | |
| # from BASH itself. | |
| outfile='pep8.html' | |
| python_power > $outfile | |
| if [[ -f $outfile ]]; then | |
| echo "New file was created: $outfile" | |
| google-chrome $outfile | |
| else | |
| echo "Unable to create new file: $outfile" | |
| fi | |
Okay updated Code, had some issues with getting it working with return value capturing, and do a workaround - which isn't a nice way when you have two processes using bselect at the same time... but I can facilitate with that for the moment.
# Name: bselect()
# Arg: selection-items
# Example:
# bselect "root $USER $username"
#
# Example: (wished I get it working to be like this example...)
# Call it and capture the output
#
# SELECTION=$(bselect "root $USER $username")
# echo "Selected User": $SELECTION
#
#
# Example: (working example, workaround with writing the selection result to a file, and in bash script to cat the file)
# Call it and capture the output
#
# bselect "root $USER $username"
# username=$(cat ~/.bselect)
# echo "Selected User": $username
#
bselect(){
read -r -d '' script <<-"----EOF"
import os
import json
from bullet import Bullet
selections = os.environ['PYTHON_ARG'].split()
print(selections)
cli = Bullet(
prompt = "\nPlease choose: ",
choices = selections,
return_index = False
)
result = cli.launch()
# print("export PYTHON_RETURN=%s" % result)
# print(result)
f = open(os.path.expanduser('~/.bselect'), 'w')
f.write(result)
f.close()
----EOF
PYTHON_ARG="$1" python -c "$script"
}
Example bash call:
bselect "root $USER $username"
username=$(cat ~/.bselect)
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Here is a example to make embedded python code working which needs a tty / pty, because it interacts with the user:
I wanted to have a sexy ui in my shell scripts, and found the python library bullet and wrapped it into my bash scripts like above described, but bullet needs a tty / pty an with here documents there is no tty / pty available. I found the following StackOverflow post and combined everything together.
Example bash call:
Preview: