gistfile1.txt

➜ make/02.files-go-source.sh | XARGS_STATE=bin/make/fmt XARGS_WRAP_OUTPUT=0 bin/xargs-if-changed bin/gofmt -l -s -w
/Users/oleg/pp/backend/src/cmd/make/xargs-if-changed/main.go
➜ bin/xargs-if-changed --help
Usage: xargs-if-changed <tool with arguments>
tool
	1. reads file paths from stdin
	2. reads content of every file and calculate MD5
	3. checks MD5 for this file in <XARGS_STATE>
	4. if file was changed executes "<tool with arguments> <file path>"
	5. if execution was successfull writes actual MD5 for <file path> to <XARGS_STATE>
environment variables:
	XARGS_STATE        <file path> path to file with state
	XARGS_WRAP_OUTPUT  <0|1>       wrap or not <tool> stdout/stderr by prefix "<file>: "
	XARGS_PARALLEL     <integer>   worker count