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A small utility library to handle arguments and read/write text to files using bash-like syntax

Project description


PyPi version Python 3.6|3.7|3.8|3.9 PRs Welcome

A small utility library to handle arguments and read/write text to files using bash-like syntax


Requires python3.6+

To install with pip, run:

pip install bash_like

This creates small helper function/symbols to handle some common patterns when creating python scripts

To use, include the following imports at the top:

from bash_like import S, SO  # (Shell, ShellOperations)
Description Bash bash_like (python)
Write a string to a file echo hello > file.txt S("hello\n") > "file.txt"
Append to file echo hello >> file.txt S("hello\n") >> "file.txt"
Print to STDERR (2) echo error 1>&2 S("error\n") > 2
Print to STDOUT (1) echo hello S("hello\n") > 1
Read text from a file <input.txt SO < "input.txt"
Read lines from a file (strips, and ignores empty lines) while read line; do echo line; done <input.txt SO << "input.txt"
Get Environment or CLI argument, If not present, print error and exit FILE="${1:?Provide file as first CLI arg}" ;VAL="${CONFIG_VAR:?Error - CONFIG_VAR is not set}" file = SO | (1, "Provide file as first CLI arg"); val = SO | ("CONFIG_VAR", "Error - CONFIG_VAR is not set")
Get Environment or CLI argument, If not present, use default FILE="${1:-output.txt}"; VAL="${DIFFERENCE:-5}" file = SO - (1, "output.txt"); val = SO - ("DIFFERENCE", 5)

Of course, you don't have to use hello for the strings, wrapping any python string in S allows you to quickly redirect it to a file, without having to do the with block:

As a more complete example, this takes a file as input, and writes the contents of that file in lower case to ${APP_DATA:-$HOME/.local/share}/..... It:

  • uses the first CLI argument as the input file, else prints an error and exits
  • uses the second CLI argument as basename, else defaults to output.txt
  • uses APP_DATA (some environment variable for your application) if present, else defaults to ~/.local/share

APP_DATA=~/.local/appdata python3 input.txt fout.txt would write to ~/.local/appdata/fout.txt

from os import path, environ
from time import time

from bash_like import S, SO

# the 1 and 2 correspond to sys.argv[1] and sys.argv[2], if they're present
inp = SO | (1, "Error: no input file provided as first argument")
out = SO - (2, "output.txt")
app_data = SO - ("APP_DATA", path.join(environ["HOME"], ".local", "share"))

# read file, casefold (lowercase), and write to file
S((SO < inp).casefold()) > path.join(app_data, out)
# append current time to a temporary logfile
S(f"{time()}\n") >> "/tmp/time.log"

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