gistfile1.txt

def local_sed(filename, before, after, limit='', use_sudo=False, backup=''):
    """
    Run a search-and-replace on ``filename`` with given regex patterns.

    Equivalent to ``sed -i<backup> -r -e "/<limit>/ s/<before>/<after>/g
    <filename>"``.

    For convenience, ``before`` and ``after`` will automatically escape forward
    slashes, single quotes and parentheses for you, so you don't need to
    specify e.g.  ``http:\/\/foo\.com``, instead just using ``http://foo\.com``
    is fine.

    To maintain compatibility with Fabric's own sed, use_sudo is included by unused.
    """
    func = local
    for char in "\&":
        after = after.replace(char, r'\%s' % char)
    # Characters to be escaped in both
    for char in "/'":
        before = before.replace(char, r'\%s' % char)
        after = after.replace(char, r'\%s' % char)
    # Characters to be escaped in replacement only (they're useful in regexen
    # in the 'before' part)
    for char in "()":
        after = after.replace(char, r'\%s' % char)
    if limit:
        limit = r'/%s/ ' % limit
    # Test the OS because of differences between sed versions
    with hide('running', 'stdout'):
        platform = local("uname", capture=True)
    if platform in ('Darwin'):
        expr = r"sed -i '%s' -e '%ss/%s/%s/g' %s"
    else:
        expr = r"sed -i%s -r -e '%ss/%s/%s/g' %s"
    command = expr % (backup, limit, before, after, filename)
    return func(command)