A command line application to apply a dictionnary (json) of substitutions to text file corpus. This program is a find-and-replace tool to perform a arbitrarily large set of substitutions in a reproducible fashion.

Disclaimer, this app is far less powerful than sed and in particular doesn't support regex replacement. What it offers a simpler interface to make simple sweeping changes across a whole project in a reproducible fashion.

The easiest installation method is

$ pip install apply-subs

In order to install apply-subs in isolation, use pipx instead.

apply-subs uses a json file as input. This file should specify substitutions as new: old, where old can either be a single str, or a list of strings.

echo "bunnies and bongos and bananas" > mytext.txt
echo '{"bunnies": "rabbits", "SECRETS": ["bongos", "bananas"]}' > mysubs.json
apply-subs mytext.txt -s mysubs.json

will print the patched content

bunnies and SECRETS and SECRETS

Use diff mode (-d/--diff) to print a diff instead of the end result

--- mytext.txt
+++ mytext.txt (patched)
@@ -1 +1 @@
-Lorem ipsum dolor sit amet, consectetur adipiscing elit
+Hello dolor sit amet, consectetur goodbye

Use -cp/--cdiff/--colored-diff for a colored output (when supported).

-i/--inplace

apply-subs --inplace mytext.txt -s mysubs.json

is equivalent to

apply-subs mytext.txt -s mysubs.json > mytext.txt

The target positional argument can consist of a single file (as illustrated above), or many. This is useful for instance if you need to apply a set of subtitutions to all files in a project whose name match a regexp.

git ls-files | egrep "(.md|.py)$" | xargs apply-subs -s subsubs.json -i