view mercurial/help/templates.txt @ 20293:2f6b3900be64

cat: increase perf when catting single files

Special case the single file case in hg cat. This allows us to avoid
parsing the manifest, which shaves 15% off hg cat perf. This is worth
it, since automation often uses hg cat for retrieving single files.

Mercurial allows you to customize output of commands through
templates. You can either pass in a template from the command
line, via the --template option, or select an existing
template-style (--style).

You can customize output for any "log-like" command: log,
outgoing, incoming, tip, parents, heads and glog.

Five styles are packaged with Mercurial: default (the style used
when no explicit preference is passed), compact, changelog, phases
and xml.
Usage::

    $ hg log -r1 --style changelog

A template is a piece of text, with markup to invoke variable
expansion::

    $ hg log -r1 --template "{node}\n"
    b56ce7b07c52de7d5fd79fb89701ea538af65746

Strings in curly braces are called keywords. The availability of
keywords depends on the exact context of the templater. These
keywords are usually available for templating a log-like command:

.. keywordsmarker

The "date" keyword does not produce human-readable output. If you
want to use a date in your output, you can use a filter to process
it. Filters are functions which return a string based on the input
variable. Be sure to use the stringify filter first when you're
applying a string-input filter to a list-like input variable.
You can also use a chain of filters to get the desired output::

   $ hg tip --template "{date|isodate}\n"
   2008-08-21 18:22 +0000

List of filters:

.. filtersmarker

Note that a filter is nothing more than a function call, i.e.
``expr|filter`` is equivalent to ``filter(expr)``.

In addition to filters, there are some basic built-in functions:

- date(date[, fmt])

- fill(text[, width])

- get(dict, key)

- if(expr, then[, else])

- ifeq(expr, expr, then[, else])

- join(list, sep)

- label(label, expr)

- rstdoc(text, style)

- strip(text[, chars])

- sub(pat, repl, expr)

Also, for any expression that returns a list, there is a list operator:

- expr % "{template}"

Some sample command line templates:

- Format lists, e.g. files::

   $ hg log -r 0 --template "files:\n{files % '  {file}\n'}"

- Join the list of files with a ", "::

   $ hg log -r 0 --template "files: {join(files, ', ')}\n"

- Format date::

   $ hg log -r 0 --template "{date(date, '%Y')}\n"

- Output the description set to a fill-width of 30::

   $ hg log -r 0 --template "{fill(desc, '30')}"

- Use a conditional to test for the default branch::

   $ hg log -r 0 --template "{ifeq(branch, 'default', 'on the main branch',
   'on branch {branch}')}\n"

- Append a newline if not empty::

   $ hg tip --template "{if(author, '{author}\n')}"

- Label the output for use with the color extension::

   $ hg log -r 0 --template "{label('changeset.{phase}', node|short)}\n"

- Invert the firstline filter, i.e. everything but the first line::

   $ hg log -r 0 --template "{sub(r'^.*\n?\n?', '', desc)}\n"

- Display the contents of the 'extra' field, one per line::

   $ hg log -r 0 --template "{join(extras, '\n')}\n"