replace_in_file — regex replace in a single file

replace_in_file runs re.subn(pattern, replacement, contents) over a single file and writes the result back. Unlike edit_file, it tolerates multiple matches; unlike apply_patch, it works on one file at a time.

Schema

Arg	Type	Required	Description
path	string	yes	Relative or absolute path. The file must exist.
pattern	string	yes	Regex pattern (Python re flavor).
replacement	string	yes	Replacement string. Supports \1, \2, … backreferences.

Example invocation

{
  "path": "src/app.py",
  "pattern": "DEBUG\\s*=\\s*True",
  "replacement": "DEBUG = False"
}

from chimera.tools.replace_in_file import ReplaceInFileTool

tool = ReplaceInFileTool()
result = tool.execute(
    {"path": "docs/changelog.md",
     "pattern": r"v(\d+)\.(\d+)\.0",
     "replacement": r"v\1.\2.1"},
    env=local_env,
)

Output sample

3 replacements made in docs/changelog.md

If the pattern matches nothing:

0 replacements made in docs/changelog.md

(no error — count == 0 is just reported).

See also

• edit_file — exact-string, single-occurrence variant.
• apply_patch — multi-file atomic edits.