Ubuntu Manpage: darcs - an advanced revision control system

NAME

       darcs - an advanced revision control system

SYNOPSIS

       darcs command <arguments|[options]>...

       Where the commands and their respective arguments are

       darcs help [<darcs_command> [darcs_subcommand]]
       darcs initialize [<directory>]
       darcs add <file|directory> ...
       darcs whatsnew [file|directory]...
       darcs record [file|directory]...
       darcs clone <repository> [<directory>]
       darcs pull [repository]...
       darcs push [repository]
       darcs move <source> ... <destination>
       darcs remove <file|directory> ...
       darcs replace <old> <new> <file> ...
       darcs log [file|directory]...
       darcs annotate [file|directory]
       darcs diff [file|directory]...
       darcs show contents [file]...
       darcs show dependencies
       darcs show files [file|directory]...
       darcs show index
       darcs show pristine
       darcs show repo
       darcs show authors
       darcs show tags
       darcs show patch-index
       darcs test [[initialization] command]
       darcs revert [file|directory]...
       darcs unrevert
       darcs amend [file|directory]...
       darcs rebase pull [repository]...
       darcs rebase apply <patchfile>
       darcs rebase suspend
       darcs rebase unsuspend
       darcs rebase edit
       darcs rebase obliterate
       darcs rebase log
       darcs rebase upgrade
       darcs rollback [file|directory]...
       darcs unrecord
       darcs obliterate
       darcs clean [file|directory]...
       darcs tag [tagname]
       darcs setpref <pref> <value>
       darcs send [repository]
       darcs apply <patchfile>
       darcs optimize clean
       darcs optimize http
       darcs optimize reorder
       darcs optimize enable-patch-index
       darcs optimize disable-patch-index
       darcs optimize compress
       darcs optimize uncompress
       darcs optimize relink
       darcs optimize upgrade
       darcs optimize cache
       darcs dist
       darcs mark-conflicts [file|directory]...
       darcs repair
       darcs convert darcs-2 <source> [<destination>]
       darcs convert export
       darcs convert import [<directory>]
       darcs fetch [repository]...

DESCRIPTION

       Unlike  conventional  revision control systems, Darcs is based on tracking changes, rather than versions:
       it can and does automatically re-order independent changes when needed. This  means  that  in  Darcs  the
       state of a repository should be regarded as a set of patches rather than a sequence of versions.

       Another  distinguishing  feature of darcs is that most commands are interactive by default. For instance,
       `darcs record' (the equivalent of what is usually called `commit')  presents  you  with  each  unrecorded
       change  and  asks  you whether it should be included in the patch to be recorded. Similarly, `darcs push'
       and `darcs pull' present you with each patch, allowing you to select which patches to push or pull.

OPTIONS

Different options are accepted by different Darcs commands. Each command's most important options are
listed in the COMMANDS section. For a full list of all options accepted by a particular command, run
`darcs command --help'.

Selecting Patches:
The --patches option yields patches with names matching an *extended* regular expression. See regex(7)
for details. The --matches option yields patches that match a logical (Boolean) expression: one or more
primitive expressions combined by grouping (parentheses) and the complement (not), conjunction (and) and
disjunction (or) operators. The C notation for logic operators (!, && and ||) can also be used.

--patches=regex is a synonym for --matches='name regex'
--hash=HASH is a synonym for --matches='hash HASH'
--from-patch and --to-patch are synonyms for
--from-match='name... and --to-match='name...
--from-hash and --to-hash are synonyms for
--from-match='hash...' and --to-match='hash...'
sensible combinations of --from-* and --to-* options are possible:
`darcs log --from-patch='html.*docu' --to-match='date 20040212'`
`darcs log --from-hash=368089c6969 --to-patch='^fix.*renamed or moved.$'`

The following primitive Boolean expressions are supported:

exact STRING - check literal STRING is equal to patch name.
name REGEX - match REGEX against patch name.
author REGEX - match REGEX against patch author.
hunk REGEX - match REGEX against contents of a hunk patch.
comment REGEX - match REGEX against the full log message.
hash HASH - match HASH against (a prefix of) the hash of a patch.
date DATE - match DATE against the patch date.
touch REGEX - match file paths for a patch.

Here are some examples:

darcs log --match 'exact "Resolve issue17: use dynamic memory allocation."'
darcs log --match 'name issue17'
darcs log --match 'name "^[Rr]esolve issue17>"'
darcs log --match 'author "David Roundy"'
darcs log --match 'author droundy'
darcs log --match 'author droundy@darcs.net'
darcs log --match 'hunk "foo = 2"'
darcs log --match 'hunk "^instance .* Foo where$"'
darcs log --match 'comment "prevent deadlocks"'
darcs log --match 'hash c719567e92c3b0ab9eddd5290b705712b8b918ef'
darcs log --match 'hash c7195'
darcs log --match 'date "2006-04-02 22:41"'
darcs log --match 'date "tea time yesterday"'
darcs log --match 'touch src/foo.c'
darcs log --match 'touch src/'
darcs log --match 'touch "src/*.(c|h)"'

COMMANDS

darcs help [<darcs_command> [darcs_subcommand]]
Without arguments, `darcs help` prints a categorized list of darcs commands and a short description
of each one. With an extra argument, `darcs help foo` prints detailed help about the darcs command
foo.

Most used/starting out:
darcs initialize [<directory>]
The `darcs initialize` command creates an empty repository in the current directory. This repository
lives in a new `_darcs` directory, which stores version control metadata and settings.

Existing files and subdirectories are not touched. You can record them with `darcs record --look-for-
adds`.

Initialize is commonly abbreviated to `init`.

Darcs currently supports three kinds of patch semantics. These are called `darcs-1`, `darcs-2`, and
`darcs-3`. They are mutually incompatible, that is, you cannot exchange patches between repos with
different semantics.

By default, patches of the new repository are in the darcs-2 semantics. However it is possible to
create a repository in darcs-1 semantics with the flag `--darcs-1`, althought this is not recommended
except for sharing patches with a project that uses patches in the darcs-1 semantics.

The `darcs-3` semantics is EXPERIMENTAL and new in version 2.16. It is included only as a technology
preview and we do NOT recommend to use it for any serious work. The on-disk format is not yet
finalized and we cannot and will not promise that later releases will work with darcs-3 repos created
with any darcs version before 3.0.

Initialize and clone commands create the preferences files in _darcs/prefs/ directory of the newly
created repository. With option --with-prefs-templates `boring` and `binaries` preferences files will
be filled with default templates. If you want to leave these files empty use --no-prefs-templates
option. If you prefer to keep the relevant settings globally, it will be convenient to add 'ALL no-
prefs-templates' to your ~/darcs/defaults file.

darcs add <file|directory> ...
Generally the working tree contains both files that should be version controlled (such as source
code) and files that Darcs should ignore (such as executables compiled from the source code). The
`darcs add` command is used to tell Darcs which files to version control.

When an existing project is first imported into a Darcs repository, it is common to run `darcs add -r
*` or `darcs record -l` to add all initial source files into darcs.

Adding symbolic links (symlinks) is not supported.

Darcs will ignore all files and folders that look "boring". The `--boring` option overrides this
behaviour.

Darcs will not add a file if another file in the same folder has the same name, except for case. The
`--case-ok` option overrides this behaviour. Windows and OS X usually use filesystems that do not
allow files a folder to have the same name except for case (for example, `ReadMe` and `README`). If
`--case-ok` is used, the repository might be unusable on those systems!

darcs whatsnew [file|directory]...
The `darcs whatsnew` command lists unrecorded changes to the working tree. If you specify a set of
files and directories, only unrecorded changes to those files and directories are listed.

With the `--summary` option, the changes are condensed to one line per file, with mnemonics to
indicate the nature and extent of the change. The `--look-for-adds` option causes candidates for
`darcs add` to be included in the summary output. WithSummary mnemonics are as follows:

* `A f` and `A d/` respectively mean an added file or directory.
* `R f` and `R d/` respectively mean a removed file or directory.
* `M f -N +M rP` means a modified file, with `N` lines deleted, `M`
lines added, and `P` lexical replacements.
* `f -> g` means a moved file or directory.
* `a f` and `a d/` respectively mean a new, but unadded, file or
directory, when using `--look-for-adds`.
* An exclamation mark (!) as in `R! foo.c`, means the change
conflicts with a change in an earlier patch. The phrase `duplicated`
means the change is identical to a change in an earlier patch.

The `--machine-readable` option implies `--summary` while making it more parsable. Modified files are
only shown as `M f`, and moves are shown in two lines: `F f` and `T g` (as in 'From f To g').

By default, `darcs whatsnew` uses Darcs' internal format for changes. To see some context (unchanged
lines) around each change, use the `--unified` option. (This option has no effect in interactive
mode.) To view changes in conventional `diff` format, use the `darcs diff` command; but note that
`darcs diff` cannot properly display changes when file renames are involved.

This command exits unsuccessfully (returns a non-zero exit status) if there are no unrecorded
changes.

darcs record [file|directory]...
The `darcs record` command is used to create a patch from changes in the working tree. If you specify
a set of files and directories, changes to other files will be skipped.

Every patch has a name, an optional description, an author and a date.

Darcs will launch a text editor (see `darcs help environment`) after the interactive selection, to
let you enter the patch name (first line) and the patch description (subsequent lines).

You can supply the patch name in advance with the `-m` option, in which case no text editor is
launched, unless you use `--edit-long-comment`.

The patch description is an optional block of free-form text. It is used to supply additional
information that doesn't fit in the patch name. For example, it might include a rationale of WHY the
change was necessary.

A technical difference between patch name and patch description, is that matching with the flag `-p`
is only done on patch names.

Finally, the `--logfile` option allows you to supply a file that already contains the patch name and
description. This is useful if a previous record failed and left a `_darcs/patch_description.txt`
file.

Each patch is attributed to its author, usually by email address (for example, `Fred Bloggs
<fred@example.net>`). Darcs looks in several places for this author string: the `--author` option,
the files `_darcs/prefs/author` (in the repository) and `~/.darcs/author` (in your home directory),
and the environment variables `$DARCS_EMAIL` and `$EMAIL`. If none of those exist, Darcs will prompt
you for an author string and write it to `~/.darcs/author`. Note that if you have more than one email
address, you can put them all in `~/.darcs/author`, one author per line. Darcs will still prompt you
for an author, but it allows you to select from the list, or to type in an alternative.

If you want to manually define any explicit dependencies for your patch, you can use the `--ask-deps`
flag. Some dependencies may be automatically inferred from the patch's content and cannot be removed.
A patch with specific dependencies can be empty.

The patch date is generated automatically. It can only be spoofed by using the `--pipe` option.

If you run record with the `--pipe` option, you will be prompted for the patch date, author, and the
long comment. The long comment will extend until the end of file or stdin is reached. This interface
is intended for scripting darcs, in particular for writing repository conversion scripts. The prompts
are intended mostly as a useful guide (since scripts won't need them), to help you understand the
input format. Here's an example of what the `--pipe` prompts look like:

What is the date? Mon Nov 15 13:38:01 EST 2004
Who is the author? David Roundy
What is the log? One or more comment lines

If a test command has been defined with `darcs setpref`, attempting to record a patch will cause the
test command to be run in a clean copy of the working tree (that is, including only recorded
changes). If the test fails, you will be offered to abort the record operation.

The `--set-scripts-executable` option causes scripts to be made executable in the clean copy of the
working tree, prior to running the test. See `darcs clone` for an explanation of the script
heuristic.

If your test command is tediously slow (e.g. `make all`) and you are recording several patches in a
row, you may wish to use `--no-test` to skip all but the final test.

To see some context (unchanged lines) around each change, use the `--unified` option.

darcs clone <repository> [<directory>]
Clone creates a copy of a repository. The optional second argument specifies a destination directory
for the new copy; if omitted, it is inferred from the source location.

By default Darcs will copy every patch from the original repository. If you expect the original
repository to remain accessible, you can use `--lazy` to avoid copying patches until they are needed
('copy on demand'). This is particularly useful when copying a remote repository with a long history
that you don't care about.

When cloning locally, Darcs automatically uses hard linking where possible. As well as saving time
and space, this enables to move or delete the original repository without affecting the copy. Hard
linking requires that the copy be on the same filesystem as the original repository, and that the
filesystem support hard linking. This includes NTFS, HFS+ and all general-purpose Unix filesystems
(such as ext, UFS and ZFS). FAT does not support hard links.

When cloning from a remote location, Darcs will look for and attempt to use packs created by `darcs
optimize http` in the remote repository. Packs are single big files that can be downloaded faster
than many little files.

Darcs clone will not copy unrecorded changes to the source repository's working tree.

You can copy a repository to a ssh url, in which case the new repository will always be complete.

It is often desirable to make a copy of a repository that excludes some patches. For example, if
releases are tagged then `darcs clone --tag .` would make a copy of the repository as at the latest
release. An untagged repository state can still be identified unambiguously by a context file, as
generated by `darcs log --context`. Given the name of such a file, the `--context` option will create
a repository that includes only the patches from that context. When a user reports a bug in an
unreleased version of your project, the recommended way to find out exactly what version they were
running is to have them include a context file in the bug report. You can also make a copy of an
untagged state using the `--to-patch` or `--to-match` options, which exclude patches *after* the
first matching patch. Because these options treat the set of patches as an ordered sequence, you may
get different results after reordering with `darcs optimize reorder`.

The `--set-scripts-executable` option causes scripts to be made executable in the working tree. A
script is any file that starts with a shebang ("#!").

The --inherit-default option is meant to support a work flow where you have different branches of the
same upstream repository and want all your branches to have the same upstream repo as the
defaultrepo. It is most useful when enabled globally by adding 'ALL --inherit-default' to your
~/darcs/defaults file.

For the clone command it means the following: If the source repository already has a defaultrepo set
(either because you cloned it or because you explicitly used the --set-default option), and both
source and target are locally valid paths on the same host, then the target repo will get the same
defaultrepo as the source repo. Otherwise the target repo gets the source repo itself as defaultrepo,
i.e. we fall back to the defalt behavior (--no-inherit-default).

darcs pull [repository]...
Pull is used to bring patches made in another repository into the current repository (that is, either
the one in the current directory, or the one specified with the `--repodir` option). Pull accepts
arguments, which are URLs from which to pull, and when called without an argument, pull will use the
repository specified at `_darcs/prefs/defaultrepo`.

The default (`--union`) behavior is to pull any patches that are in any of the specified
repositories. If you specify the `--intersection` flag, darcs will only pull those patches which are
present in all source repositories. If you specify the `--complement` flag, darcs will only pull
elements in the first repository that do not exist in any of the remaining repositories.

If `--reorder` is supplied, the set of patches that exist only in the current repository is brought
at the top of the current history. This will work even if there are no new patches to pull.

For the commands push, pull, and send it means the following: Changes the meaning of the --set-
default option so that it sets the (local) defaultrepo to the defaultrepo of the remote repo, instead
of the remote repo itself. This happens only if the remote repo does have a defaultrepo set and both
local and remote repositories are locally valid paths on the same host, otherwise fall back to the
default behavior (--no-inherit-default).

See `darcs help apply` for detailed description of many options.

darcs push [repository]
Push is the opposite of pull. Push allows you to copy patches from the current repository into
another repository.

The --reorder-patches option works in the same way as it does for pull and apply: instead of placing
the new patches (coming from your local repository) on top of (i.e. after) the existing (remote)
ones, it puts the remote-only patches on top of the ones that you are pushing. This can be useful,
for instance, if you have recorded a tag locally and want this tag to be clean in the remote
repository after pushing.

If you give the `--apply-as` flag, darcs will use `sudo` to apply the patches as a different user.
This can be useful if you want to set up a system where several users can modify the same repository,
but you don't want to allow them full write access. This isn't secure against skilled malicious
attackers, but at least can protect your repository from clumsy, inept or lazy users.

`darcs push` will compress the patch data before sending it to a remote location via ssh. This works
as long as the remote darcs is not older than version 2.5. If you get errors that indicate a corrupt
patch bundle, you should try again with the `--no-compress` option.

Preparing patches before recording:
darcs move <source> ... <destination>
Darcs cannot reliably distinguish between a file being deleted and a new one added, and a file being
moved. Therefore Darcs always assumes the former, and provides the `darcs mv` command to let Darcs
know when you want the latter. This command will also move the file in the working tree (unlike
`darcs remove`), unless it has already been moved.

Darcs will not rename a file if another file in the same folder has the same name, except for case.
The `--case-ok` option overrides this behaviour. Windows and OS X usually use filesystems that do
not allow files a folder to have the same name except for case (for example, `ReadMe` and `README`).
If `--case-ok` is used, the repository might be unusable on those systems!

darcs remove <file|directory> ...
The `darcs remove` command exists primarily for symmetry with `darcs add`, as the normal way to
remove a file from version control is simply to delete it from the working tree. This command is
only useful in the unusual case where one wants to record a removal patch WITHOUT deleting the copy
in the working tree (which can be re-added).

Note that applying a removal patch to a repository (e.g. by pulling the patch) will ALWAYS affect the
working tree of that repository.

darcs replace <old> <new> <file> ...
In addition to line-based patches, Darcs supports a limited form of lexical substitution. Files are
treated as sequences of words, and each occurrence of the old word is replaced by the new word. This
is intended to provide a clean way to rename a function or variable. Such renamings typically affect
lines all through the source code, so a traditional line-based patch would be very likely to conflict
with other branches, requiring manual merging.

Files are tokenized according to one simple rule: words are strings of valid token characters, and
everything between them (punctuation and whitespace) is discarded. By default, valid token characters
are letters, numbers and the underscore (i.e. `[A-Za-z0-9_]`). However if the old and/or new token
contains either a hyphen or period, BOTH hyphen and period are treated as valid (i.e. `[A-Za-
z0-9_.-]`).

The set of valid characters can be customized using the `--token-chars` option. The argument must be
surrounded by square brackets. If a hyphen occurs between two characters in the set, it is treated as
a set range. For example, in most locales `[A-Z]` denotes all uppercase letters. If the first
character is a caret, valid tokens are taken to be the complement of the remaining characters. For
example, `[^:0` could be used to match fields in the passwd(5), where records and fields are
separated by newlines and colons respectively.

If you choose to use `--token-chars`, you are STRONGLY encouraged to do so consistently. The
consequences of using multiple replace patches with different `--token-chars` arguments on the same
file are not well tested nor well understood.

By default Darcs will refuse to perform a replacement if the new token is already in use, because the
replacements would be not be distinguishable from the existing tokens. This behaviour can be
overridden by supplying the `--force` option, but an attempt to `darcs rollback` the resulting patch
will affect these existing tokens.

Limitations:

The tokenizer treats files as byte strings, so it is not possible for `--token-chars` to include
multi-byte characters, such as the non-ASCII parts of UTF-8. Similarly, trying to replace a "high-
bit" character from a unibyte encoding will also result in replacement of the same byte in files with
different encodings. For example, an acute a from ISO 8859-1 will also match an alpha from ISO
8859-7.

Due to limitations in the patch file format, `--token-chars` arguments cannot contain literal
whitespace. For example, `[^ ]` cannot be used to declare all characters except the space, tab and
newline as valid within a word, because it contains a literal space.

Unlike POSIX regex(7) bracket expressions, character classes (such as `[[:alnum:]]`) are NOT
supported by `--token-chars`, and will be silently treated as a simple set of characters.

Querying the repository:
darcs log [file|directory]...
The `darcs log` command lists patches of the current repository or, with `--repo`, a remote
repository. Without options or arguments, ALL patches will be listed.

When given files or directories paths as arguments, only patches which affect those paths are listed.
This includes patches that happened to files before they were moved or renamed.

When given `--from-tag` or `--from-patch`, only patches since that tag or patch are listed.
Similarly, the `--to-tag` and `--to-patch` options restrict the list to older patches.

The `--last` and `--max-count` options both limit the number of patches listed. The former applies
BEFORE other filters, whereas the latter applies AFTER other filters. For example `darcs log foo.c
--max-count 3` will print the last three patches that affect foo.c, whereas `darcs log --last 3
foo.c` will, of the last three patches, print only those that affect foo.c.

Four output formats exist. The default is `--human-readable`. The slightly different `--machine-
readable` format enables to see patch dependencies in non-interactive mode. You can also select
`--context`, which is an internal format that can be re-read by Darcs (e.g. `darcs clone --context`).

Finally, there is `--xml-output`, which emits valid XML... unless a the patch metadata (author, name
or description) contains a non-ASCII character and was recorded in a non-UTF8 locale.

darcs annotate [file|directory]
When `darcs annotate` is called on a file, it will find the patch that last modified each line in
that file. This also works on directories.

The `--machine-readable` option can be used to generate output for machine postprocessing.

darcs diff [file|directory]...
The `darcs diff` command compares two versions of the working tree of the current repository.
Without options, the pristine (recorded) and unrecorded working trees are compared. This is lower-
level than the `darcs whatsnew` command, since it outputs a line-by-line diff, and it is also slower.
As with `darcs whatsnew`, if you specify files or directories, changes to other files are not listed.
The command always uses an external diff utility.

With the `--patch` option, the comparison will be made between working trees with and without that
patch. Patches *after* the selected patch are not present in either of the compared working trees.
The `--from-patch` and `--to-patch` options allow the set of patches in the `old' and `new' working
trees to be specified separately.

The associated tag and match options are also understood, e.g. `darcs diff --from-tag 1.0 --to-tag
1.1`. All these options assume an ordering of the patch set, so results may be affected by
operations such as `darcs optimize reorder`.

diff(1) is always called with the arguments `-rN` and by default also with `-u` to show the
differences in unified format. This can be turned off by passing `--no-unified`. An additional
argument can be passed using `--diff-opts`, such as `--diff-opts=-ud` or `--diff-opts=-wU9`.

The `--diff-command` option can be used to specify an alternative utility. Arguments may be included,
separated by whitespace. The value is not interpreted by a shell, so shell constructs cannot be
used. The arguments %1 and %2 MUST be included, these are substituted for the two working trees
being compared. For instance:

darcs diff -p . --diff-command "meld %1 %2"

If this option is used, `--diff-opts` is ignored.

darcs show subcommand
Display various information about a repository. See description of the subcommands for details.

darcs show contents [file]...
Show contents can be used to display an earlier version of some file(s). If you give show contents
no version arguments, it displays the recorded version of the file(s).

darcs show dependencies
This command creates a graph of the dependencies between patches. The output format is the Dot
Language, see https://www.graphviz.org/doc/info/lang.html. The resulting graph is transitively
reduced, in other words, it contains only the direct dependencies, not the indirect ones.

By default all patches in your repository are considered. You can limit this to a range of patches
using patch matching options, see `darcs help patterns` and the options avaiable for this command.
For instance, to visualize the dependencies between all patches since the last tag, do:

darcs show dependencies --from-tag=. | dot -Tpdf -o FILE.pdf

This command can take a very(!) long time to compute its result, depending on the number of patches
in the selected range. For N patches it needs to do on the order of N^3 commutations in the worst
case.

darcs show files [file|directory]...
The `darcs show files` command lists those files and directories in the working tree that are under
version control. This command is primarily for scripting purposes; end users will probably want
`darcs whatsnew --summary`.

A file is "pending" if it has been added but not recorded. By default, pending files (and
directories) are listed; the `--no-pending` option prevents this.

By default `darcs show files` lists both files and directories, but the `--no-files` and `--no-
directories` flags modify this behaviour.

By default entries are one-per-line (i.e. newline separated). This can cause problems if the files
themselves contain newlines or other control characters. To get around this, the `--null` option
uses the null character instead. The script interpreting output from this command needs to
understand this idiom; `xargs -0` is such a command.

For example, to list version-controlled files by size:

darcs show files -0 | xargs -0 ls -ldS

darcs show index
The `darcs show index` command lists all version-controlled files and directories along with their
hashes as stored in `_darcs/index`. For files, the fields correspond to file size, sha256 of the
current file content and the filename.

darcs show pristine
The `darcs show pristine` command lists all version-controlled files and directories along with the
hashes of their pristine copies. For files, the fields correspond to file size, sha256 of the
pristine file content and the filename.

darcs show repo
The `darcs show repo` command displays statistics about the current repository, allowing third-party
scripts to access this information without inspecting `_darcs` directly (and without breaking when
the `_darcs` format changes).

The 'Weak Hash' identifies the set of patches of a repository independently of ordering. It can be
used to easily compare two repositories of a same project. It is not cryptographically secure.

By default, output includes statistics that require walking through the patches recorded in the
repository, namely the 'Weak Hash' and the count of patches. If this data isn't needed, use `--no-
enum-patches` to accelerate this command from O(n) to O(1).

By default, output is in a human-readable format. The `--xml-output` option can be used to generate
output for machine postprocessing.

darcs show authors
The `darcs show authors` command lists the authors of the current repository, sorted by the number of
patches contributed. With the `--verbose` option, this command simply lists the author of each patch
(without aggregation or sorting).

An author's name or email address may change over time. To tell Darcs when multiple author strings
refer to the same individual, create an `.authorspellings` file in the root of the working tree.
Each line in this file begins with an author's canonical name and address, and may be followed by a
comma separated list of extended regular expressions. Blank lines and lines beginning with two
hyphens are ignored. The format of `.authorspelling` can be described by this pattern:

name <address> [, regexp ]*

There are some pitfalls concerning special characters: Whitespaces are stripped, if you need space in
regexp use [ ]. Because comma serves as a separator you have to escape it if you want it in regexp.
Note that `.authorspelling` use extended regular expressions so +, ? and so on are metacharacters and
you need to escape them to be interpreted literally.

Any patch with an author string that matches the canonical address or any of the associated regexps
is considered to be the work of that author. All matching is case-insensitive and partial (it can
match a substring). Use ^,$ to match the whole string in regexps

Currently this canonicalization step is done only in `darcs show authors`. Other commands, such as
`darcs log` use author strings verbatim.

An example `.authorspelling` file is:

-- This is a comment.
Fred Nurk <fred@example.com>
John Snagge <snagge@bbc.co.uk>, John, snagge@, js@(si|mit).edu
Chuck Jones Jr. <chuck@pobox.com>, cj+user@example.com

darcs show tags
The tags command writes a list of all tags in the repository to standard output.

Tab characters (ASCII character 9) in tag names are changed to spaces for better interoperability
with shell tools. A warning is printed if this happens.

darcs show patch-index
When given the `--verbose` flag, the command dumps the complete content of the patch index and checks
its integrity.

darcs test [[initialization] command]
Run test on the current recorded state of the repository. Given no arguments, it uses the default
repository test (see `darcs setpref`). Given one argument, it treats it as a test command. Given
two arguments, the first is an initialization command and the second is the test (meaning the exit
code of the first command is not taken into account to determine success of the test). If given the
`--linear` or `--bisect` flags, it tries to find the most recent version in the repository which
passes a test.

`--linear` does linear search starting from head, and moving away from head. This strategy is best
when the test runs very quickly or the patch you're seeking is near the head.

`--bisect` does binary search. This strategy is best when the test runs very slowly or the patch
you're seeking is likely to be in the repository's distant past.

`--backoff` starts searching from head, skipping further and further into the past until the test
succeeds. It then does a binary search on a subset of those skipped patches. This strategy works
well unless the patch you're seeking is in the repository's distant past.

Under the assumption that failure is monotonous, `--linear` and `--bisect` produce the same result.
(Monotonous means that when moving away from head, the test result changes only once from "fail" to
"ok".) If failure is not monotonous, any one of the patches that break the test is found at random.

If the test command returns an exit code of 125, the repository state is treated as "untestable" -
for example you might get it to do this for a build break or other result that isn't the actual
problem you want to track down. This can lead to multiple patches being reported as the source of the
failure.

For example, if patch 1 introduces a build break, patch 2 breaks a test in an unrelated bit of the
code, and patch 3 fixes the build break, then patches 1,2 and 3 would be identified as causing the
failure.

The `--shrink-failures` option, on by default, adds a post-processing step to reorder patches to try
to narrow down a failure more precisely. In the example above, it's likely that patch 2 could be
moved before patch 1 or after patch 3, allowing it to be identified as the sole cause of the failure.

This shrinking can be disabled with `--no-shrink-failures`.

Undoing and correcting:
darcs revert [file|directory]...
The `darcs revert` command discards unrecorded changes in the working tree. As with `darcs record`,
you will be asked which hunks (changes) to revert. The `--all` switch can be used to avoid such
prompting. If files or directories are specified, other parts of the working tree are not reverted.

In you accidentally reverted something you wanted to keep (for example, typing `darcs rev -a` instead
of `darcs rec -a`), you can immediately run `darcs unrevert` to restore it. This is only guaranteed
to work if the repository has not changed since `darcs revert` ran.

darcs unrevert
Unrevert is a rescue command in case you accidentally reverted something you wanted to keep (for
example, typing `darcs rev -a` instead of `darcs rec -a`).

This command may fail if the repository has changed since the revert took place. Darcs will ask for
confirmation before executing an interactive command that will DEFINITELY prevent unreversion.

darcs amend [file|directory]...
Amend updates a "draft" patch with additions or improvements, resulting in a single "finished" patch.

By default `amend` proposes you to record additional changes. If instead you want to remove changes,
use the flag `--unrecord`.

When recording a draft patch, it is a good idea to start the name with `DRAFT:`. When done, remove
it with `darcs amend --edit-long-comment`. Alternatively, to change the patch name without starting
an editor, use the `--name`/`-m` flag:

darcs amend --match 'name "DRAFT: foo"' --name 'foo2'

Like `darcs record`, if you call amend with files as arguments, you will only be asked about changes
to those files. So to amend a patch to foo.c with improvements in bar.c, you would run:

darcs amend --match 'touch foo.c' bar.c

Note that this command edits the history of your repo. It is primarily intended to be used on patches
that you authored yourself and did not yet publish. Using it for patches that are already published,
or even ones you did not author yourself, may cause confusion and can disrupt your own and other
people's work-flow. This depends a lot on how your project is organized, though, so there may be
valid exceptions to this rule.

Using the `--not-in-remote` option is a good way to guard against accidentally editing published
patches. Without arguments, this deselects any patches that are also present in the `defaultrepo`. If
you work in a clone of some publically hosted repository, then your `defaultrepo` will be that public
repo. You can also give the option an argument which is a path or URL of some other repository; you
can use the option multiple times with different repositories, which has the effect of treating all
of them as "upstream", that is, it prevents you from selecting a patch that is contained in any of
these repos.

You can also guard only against editing another developer's patch by using an appropriate `--match`
option with the `author` keyword. For instance, you could add something like `<cmd> match Your Name`
to your `~/.darcs/defaults`.

darcs rebase subcommand
The `darcs rebase' command is used to edit a collection of darcs patches.

The basic idea is that you can suspend patches from the end of a repository. These patches are no
longer part of the history and have no effect on the working tree. Suspended patches are invisible to
commands that access the repository from the outside, such as push, pull, clone, send, etc.

The sequence of suspended patches can be manipulated in ways that are not allowed for normal patches.
For instance, `darcs rebase obliterate` allows you to remove a patch in this sequence, even if other
suspended patches depend on it. These other patches will as a result become conflicted.

You can also operate on the normal patches in the usual way. If you add or remove normal patches, the
suspended patches will be automatically adapted to still apply to the pristine state, possibly
becoming conflicted in the course.

Note that as soon as a patch gets suspended, it will irrevocably loose its identity. This means that
suspending a patch is subject to the usual warnings about editing the history of your project.

The opposite of suspending a patch is to unsuspend it. This turns it back into a normal patch. If the
patch is conflicted as a result of previous operations on either the normal patches or the suspended
patches, unsuspending will create appropriate conflict markup. Note, however, that the unsuspended
patch itself WILL NOT BE CONFLICTED itself. This means that there is no way to re-generate the
conflict markup. Once you removed it, by editing files or using `darcs revert`, any information about
the conflict is lost.

As long as you have suspended patches, darcs will display a short message after each command to
remind you that your patch editing operation is still in progress.

darcs rebase pull [repository]...
Copy and apply patches from another repository, suspending any local patches that conflict.

darcs rebase apply <patchfile>
Apply a patch bundle, suspending any local patches that conflict.

darcs rebase suspend
Select patches to move into a suspended state at the end of the repo.

darcs rebase unsuspend
Select suspended patches to restore to the end of the repo.

darcs rebase edit
Edit suspended patches.

darcs rebase obliterate
Obliterate a patch that is currently suspended.

darcs rebase log
List the currently suspended changes.

darcs rebase upgrade
Upgrade a repo with an old-style rebase in progress.

Doing this means you won't be able to use darcs version < 2.15 with this repository until the rebase
is finished.

darcs rollback [file|directory]...
Rollback is used to undo the effects of some changes from patches in the repository. The selected
changes are undone in your working tree, but the repository is left unchanged. First you are offered
a choice of which patches to undo, then which changes within the patches to undo.

Before doing `rollback`, you may want to temporarily undo the changes of your working tree (if there
are) and save them for later use. To do so, you can run `revert`, then run `rollback`, record a
patch, and run `unrevert` to restore the saved changes into your working tree.

darcs unrecord
Unrecord does the opposite of record: it deletes patches from the repository without changing the
working tree. The changes are now again visible with `darcs whatsnew` and you can record or revert
them as you please.

darcs obliterate
Obliterate completely removes recorded patches from your local repository. The changes will be undone
in your working tree and the patches will not be shown in your changes list anymore. Beware that you
can lose precious code by obliterating!

One way to save obliterated patches is to use the -O flag. A patch bundle will be created locally,
that you will be able to apply later to your repository with `darcs apply`. See `darcs send` for a
more detailed description.

darcs clean [file|directory]...
Remove unrecorded changes from the working tree.

This is an alias for `darcs revert -l/--look-for-adds` which means it works also on files that have
not been added. You can additionally pass `--boring` to get rid of *every* unrecorded file or
directory.

See description of `darcs revert` for more details.

Direct modification of the repository:
darcs tag [tagname]
The `darcs tag` command names the current repository state, so that it can easily be referred to
later. It does so by recording a special kind of patch that makes no changes and which explicitly
depends on all patches currently existing in the repository (except for those which are depended upon
by other tags already in the repository). In the common case of a sequential series of tags, this
means that the tag depends on all patches since the last tag, plus that tag itself.

Every *important* state should be tagged; in particular it is good practice to tag each stable
release with a number or codename. Advice on release numbering can be found at
<http://producingoss.com/en/development-cycle.html>.

To reproduce the state of a repository `R` as at tag `t`, use the command `darcs clone --tag t R`.
Note however that tags are matched as regular expressions, like with `--patch`. To make sure you get
the right tag it may be better to use `darcs clone --tag '^t$'`. The command `darcs show tags` lists
all tags in the current repository.

Tagging also provides significant performance benefits: when Darcs reaches a tag that depends on all
preceding patches, it can often stop processing. A tag in such a position is called "clean". For
instance, operations like push and pull need to examine only patches that come after the latest
shared clean tag.

Like normal patches, a tag has a name, an author, a timestamp and an optional long description, but
it does not change the working tree. A tag can have any name, but it is generally best to pick a
naming scheme and stick to it.

By default a tag names the entire repository state at the time the tag is created. If the --ask-deps
option is used, the patches to include as part of the tag can be explicitly selected.

The `darcs tag` command accepts the `--pipe` option, which behaves as described in `darcs record`.

darcs setpref <pref> <value>
When working on project with multiple repositories and contributors, it is sometimes desirable for a
preference to be set consistently project-wide. This is achieved by treating a preference set with
`darcs setpref` as an unrecorded change, which can then be recorded and then treated like any other
patch.

Valid preferences are:

* test -- a shell command that runs regression tests * predist -- a shell command to run before
`darcs dist' * boringfile -- the path to a version-controlled boring file * binariesfile -- the path
to a version-controlled binaries file

For example, a project using GNU autotools, with a `make test` target to perform regression tests,
might enable Darcs' integrated regression testing with the following command:

darcs setpref test 'autoconf && ./configure && make && make test'

Note that merging is not currently implemented for preferences: if two patches attempt to set the
same preference, the last patch applied to the repository will always take precedence. This is
considered a low-priority bug, because preferences are seldom set.

Exchanging patches by e-mail:
darcs send [repository]
Send is used to prepare a bundle of patches that can be applied to a target repository. Send accepts
the URL of the repository as an argument. When called without an argument, send will use the most
recent repository that was either pushed to, pulled from or sent to. By default, the patch bundle is
saved to a file, although you may directly send it by mail.

The `--output`, `--output-auto-name`, and `--to` flags determine what darcs does with the patch
bundle after creating it. If you provide an `--output` argument, the patch bundle is saved to that
file. If you specify `--output-auto-name`, the patch bundle is saved to a file with an automatically
generated name. If you give one or more `--to` arguments, the bundle of patches is sent to those
locations. The locations may either be email addresses or urls that the patch should be submitted to
via HTTP.

If you provide the `--mail` flag, darcs will look at the contents of the `_darcs/prefs/email` file in
the target repository (if it exists), and send the patch by email to that address. In this case, you
may use the `--cc` option to specify additional recipients without overriding the default repository
email address.

If `_darcs/prefs/post` exists in the target repository, darcs will upload to the URL contained in
that file, which may either be a `mailto:` URL, or an `http://` URL. In the latter case, the patch is
posted to that URL.

If there is no email address associated with the repository, darcs will prompt you for an email
address.

Use the `--subject` flag to set the subject of the e-mail to be sent. If you don't provide a subject
on the command line, darcs will make one up based on names of the patches in the patch bundle.

Use the `--in-reply-to` flag to set the In-Reply-To and References headers of the e-mail to be sent.
By default no additional headers are included so e-mail will not be treated as reply by mail readers.

If you want to include a description or explanation along with the bundle of patches, you need to
specify the `--edit-description` flag, which will cause darcs to open up an editor with which you can
compose a message to go along with your patches.

If you want to use a command different from the default one for sending email, you need to specify a
command line with the `--sendmail-command` option. The command line can contain some format
specifiers which are replaced by the actual values. Accepted format specifiers are `%s` for subject,
`%t` for to, `%c` for cc, `%b` for the body of the mail, `%f` for from, `%a` for the patch bundle and
the same specifiers in uppercase for the URL-encoded values. Additionally you can add `%<` to the end
of the command line if the command expects the complete email message on standard input. E.g. the
command lines for evolution and msmtp look like this:

evolution "mailto:%T?subject=%S&attach=%A&cc=%C&body=%B"
msmtp -t %<

Do not confuse the `--author` options with the return address that `darcs send` will set for your
patch bundle.

For example, if you have two email addresses A and B:

* If you use `--author A` but your machine is configured to send
mail from address B by default, then the return address on your
message will be B.
* If you use `--from A` and your mail client supports setting the
From: address arbitrarily (some non-Unix-like mail clients,
especially, may not support this), then the return address will
be A; if it does not support this, then the return address will
be B.
* If you supply neither `--from` nor `--author` then the return
address will be B.

In addition, unless you specify the sendmail command with `--sendmail-command`, darcs sends email
using the default email command on your computer. This default command is determined by the
`configure` script. Thus, on some non-Unix-like OSes, `--from` is likely to not work at all.

darcs apply <patchfile>
The `darcs apply` command takes a patch bundle and attempts to insert it into the current repository.
In addition to invoking it directly on bundles created by `darcs send`, it is used internally by
`darcs push` on the remote end of an SSH connection.

If no file is supplied, the bundle is read from standard input.

If given an email instead of a patch bundle, Darcs will look for the bundle as a MIME attachment to
that email. Currently this will fail if the MIME boundary is rewritten, such as in Courier and
Mail.app.

If gpg(1) is installed, you can use `--verify pubring.gpg` to reject bundles that aren't signed by a
key in `pubring.gpg`.

If `--test` is supplied and a test is defined (see `darcs setpref`), the bundle will be rejected if
the test fails after applying it.

Unlike most Darcs commands, `darcs apply` defaults to `--all`. Use the `--interactive` option to pick
which patches to apply from a bundle.

A patch bundle may introduce unresolved conflicts with existing patches or with the working tree. By
default, Darcs will refuse to apply conflicting patches (`--no-allow-conflicts`).

The `--mark-conflicts` option instructs Darcs to allow conflicts and try to add conflict markup in
your working tree. Note that this may (partly) fail, because some conflicts cannot be marked, such as
e.g. conflicts between two adds of the same file. In this case Darcs will warn you and display the
conflicting changes instead. When Darcs detects conflicts with unrecorded changes, it will give you
an extra warning and prompts you to confirm that you want to continue. This is because your original
unrecorded changes cannot be automatically restored by Darcs.

Note that conflict markup is something Darcs adds to your working tree files. Nevertheless, you can
always re-construct it using `darcs mark-conflicts`.

The `--external-merge` option lets you resolve conflicts using an external merge tool. In the option,
`%a` is replaced with the common ancestor (merge base), `%1` with the first version, `%2` with the
second version, and `%o` with the path where your resolved content should go. For example, to use the
xxdiff visual merge tool you'd specify: `--external-merge='xxdiff -m -O -M %o %1 %a %2'`

The `--allow-conflicts` option allows conflicts but does not add conflict markup. This is useful
when you want to treat a repository as just a bunch of patches, such as using `darcs pull --union` to
download all of your co-workers' patches before going offline. Again, conflict markup can be added at
any time later on using `darcs mark-conflicts`.

For more information on conflicts in Darcs and how to resolve them, see the help on `darcs mark-
conflicts`.

Other commands:
darcs optimize subcommand
The `darcs optimize` command modifies internal data structures of the current repository in an
attempt to reduce its resource requirements.

For further details see the descriptions of the subcommands.

darcs optimize clean
Darcs normally does not delete hashed files that are no longer referenced by the current repository
state. This command can be use to get rid of these files to save some disk space.

darcs optimize http
Using this option creates 'repository packs' that can dramatically speed up performance when a user
does a `darcs clone` of the repository over HTTP. To make use of packs, the clients must have a darcs
of at least version 2.10.

darcs optimize reorder
This command moves recent patches (those not included in the latest tag) to the "front", reducing the
amount that a typical remote command needs to download. It should also reduce the CPU time needed for
some operations. This is the behavior with --shallow which is the default.

With the --deep option it tries to optimize all tags in the whole repository. This breaks the
history of patches into smaller bunches, which can further improve efficiency, but requires all
patches to be present. It is therefore less suitable for lazy clones.

darcs optimize enable-patch-index
Build the patch index, an internal data structure that accelerates commands that need to know what
patches touch a given file. Such as annotate and log.

darcs optimize disable-patch-index
Delete and stop maintaining the patch index from the repository.

darcs optimize compress
Patches, inventories, and pristine files are compressed with zlib (RFC 1951) to reduce storage (and
download) size. Older darcs versions allowed to store them uncompressed, and darcs is still able to
read those files if they are not compressed.

The `darcs optimize uncompress` and `darcs optimize compress` commands can be used to ensure existing
patches in the current repository are respectively uncompressed or compressed.

darcs optimize uncompress
Patches, inventories, and pristine files are compressed with zlib (RFC 1951) to reduce storage (and
download) size. Older darcs versions allowed to store them uncompressed, and darcs is still able to
read those files if they are not compressed.

The `darcs optimize uncompress` and `darcs optimize compress` commands can be used to ensure existing
patches in the current repository are respectively uncompressed or compressed.

darcs optimize relink
The `darcs optimize relink` command hard-links patches that the current repository has in common with
its peers. Peers are those repositories listed in `_darcs/prefs/sources`, or defined with the
`--sibling` option (which can be used multiple times).

Darcs uses hard-links automatically, so this command is rarely needed. It is most useful if you used
`cp -r` instead of `darcs clone` to copy a repository, or if you pulled the same patch from a remote
repository into multiple local repositories.

darcs optimize upgrade
Convert old-fashioned repositories to the current default hashed format.

darcs optimize cache
This command deletes obsolete files within the global cache.

It also automatically migrates the global cache to the (default) bucketed format.

darcs dist
`darcs dist` creates a compressed archive in the repository's root directory, containing the recorded
state of the working tree (unrecorded changes and the `_darcs` directory are excluded). The command
accepts matchers to create an archive of some past repository state, for instance `--tag`.

By default, the archive (and the top-level directory within the archive) has the same name as the
repository, but this can be overridden with the `--dist-name` option.

If a predist command is set (see `darcs setpref`), that command will be run on the recorded state
prior to archiving. For example, autotools projects would set it to `autoconf && automake`.

If `--zip` is used, matchers and the predist command are ignored.

darcs mark-conflicts [file|directory]...
Darcs requires human guidance to reconcile independent changes to the same part of a file. When a
conflict first occurs, darcs will add the initial state and all conflicting choices to the working
tree, delimited by the markers `v v v`, `=====`, `* * *` and `^ ^ ^`, as follows:

v v v v v v v
initial state
=============
first choice
*************
...more choices...
*************
last choice
^ ^ ^ ^ ^ ^ ^

If you happened to revert or manually delete this conflict markup without actually resolving the
conflict, `darcs mark-conflicts` can be used to re-create it; and similarly if you have used `darcs
apply` or `darcs pull` with `--allow-conflicts`, where conflicts aren't marked initially.

In Darcs, a conflict counts as resolved when all of the changes involved in the conflict (which can
be more than two) are depended on by one or more later patches. If you record a resolution for a
particular conflict, `darcs mark-conflicts` will no longer mark it, indicating that it is resolved.
If you have unrecorded changes, these count as (potential) conflict resolutions, too, just as if you
had already recorded them.

This principle extends to explicit "semantic" dependencies. For instance, recording a tag will
automatically mark all conflicts as resolved.

In the above schematic example the "initial state" corresponds to the recorded state of the file in
your repository. That is to say, the recorded effect of a conflict is to apply none of the
conflicting changes. This is usually not a state you would regard as a successful resolution of the
conflict; but there are exceptional situations where this may be exactly what you want. In order to
tell Darcs that you want this conflict to be regarded as resolved, use `darcs record --ask-deps` to
record a patch that explicitly depends on all patches involved in the conflict.

darcs repair
The `darcs repair` command attempts to fix corruption in the current repository. It works by
successively applying all patches in the repository to an empty tree, each time checking that the
patch can be cleanly applied to the current pristine tree. If we detect a problem, we try to repair
the patch. Finally we compare the existing pristine with the newly reconstructed one and if they
differ, replace the existing one. Any problem encountered is reported. The flag `--dry-run` makes
this operation read-only and causes it to exit unsuccessfully (with a non-zero exit status) in case
any problems are enountered.

darcs convert subcommand
Convert repositories between various formats.

See description of the subcommands for details.

darcs convert darcs-2 <source> [<destination>]
This command converts a repository that uses the old patch semantics `darcs-1` to a new repository
with current `darcs-2` semantics.

WARNING: the repository produced by this command is not understood by Darcs 1.x, and patches cannot
be exchanged between repositories in darcs-1 and darcs-2 formats. Also, you should not exchange
patches between repositories created by different invocations of this command. This means: - Before
doing this conversion, you should merge into this repo any patches
existing elsewhere that you might want to merge in future, so that they
will remain mergeable. (You can always remove them again after converting). - After converting,
you should tell everyone with a fork of this repo
to discard it and make a new fork of the converted repo.

darcs convert export
This command enables you to export darcs repositories into git.

For a one-time export you can use the recipe:

$ cd repo
$ git init ../mirror
$ darcs convert export | (cd ../mirror && git fast-import)

For incremental export using marksfiles:

$ cd repo
$ git init ../mirror
$ touch ../mirror/git.marks
$ darcs convert export --read-marks darcs.marks --write-marks darcs.marks
| (cd ../mirror && git fast-import --import-marks=git.marks --export-marks=git.marks)

In the case of incremental export, be careful to never amend, delete or reorder patches in the source
darcs repository.

Also, be aware that exporting a darcs repo to git will not be exactly faithful in terms of history if
the darcs repository contains conflicts.

Limitations:

* Empty directories are not supported by the fast-export protocol.
* Unicode filenames are currently not correctly handled.
See http://bugs.darcs.net/issue2359 .

darcs convert import [<directory>]
This command imports git repositories into new darcs repositories. Further options are accepted (see
`darcs help init`).

To convert a git repo to a new darcs one you may run:

$ (cd gitrepo && git fast-export --all -M) | darcs convert import darcsmirror

WARNING: git repositories with branches will produce weird results,
use at your own risks.

Incremental import with marksfiles is currently not supported.

darcs fetch [repository]...
Fetch is similar to `pull` except that it does not apply any patches to the current repository.
Instead, it generates a patch bundle that you can apply later with `apply`.

Fetch's behaviour is essentially similar to pull's, so please consult the help of `pull` to know
more.

ENVIRONMENT

HOME and APPDATA
Per-user preferences are set in $HOME/.darcs (on Unix) or %APPDATA%/darcs (on Windows). This is also the
default location of the cache.

DARCS_EDITOR, VISUAL, and EDITOR
To edit a patch description of email comment, Darcs will invoke an external editor. Your preferred
editor can be set as any of the environment variables $DARCS_EDITOR, $VISUAL or $EDITOR. If none of
these are set, nano is used. If nano crashes or is not found in your PATH, vi, emacs, emacs -nw and (on
Windows) edit are each tried in turn.

DARCS_PAGER and PAGER
Darcs will invoke a pager if the output of some command is longer than 20 lines. Darcs will use the pager
specified by $DARCS_PAGER or $PAGER. If neither are set, `less` will be used. Set $DARCS_PAGER - or
$PAGER if the former is not set - to the empty string in order not to use a pager.

DARCS_DONT_COLOR, DARCS_ALWAYS_COLOR, and DARCS_ALTERNATIVE_COLOR
If the terminal understands ANSI color escape sequences, darcs will highlight certain keywords and
delimiters when printing patches, and also print hunk lines in color according to whether they are
removed or added. This can be turned off by setting the environment variable DARCS_DONT_COLOR to 1. If
you use a pager that happens to understand ANSI colors, like `less -R`, darcs can be forced always to
highlight the output by setting DARCS_ALWAYS_COLOR to 1. If you can't see colors you can set
DARCS_ALTERNATIVE_COLOR to 1, and darcs will use ANSI codes for bold and reverse video instead of colors.

DARCS_DONT_ESCAPE_TRAILING_SPACES and DARCS_DONT_ESCAPE_TRAILING_CR
By default darcs will escape (by highlighting if possible) any kind of spaces at the end of lines when
showing patch contents. If you don't want this you can turn it off by setting
DARCS_DONT_ESCAPE_TRAILING_SPACES to 1. A special case exists for only carriage returns:
DARCS_DONT_ESCAPE_TRAILING_CR

DARCS_DONT_ESCAPE_ANYTHING, DARCS_DONT_ESCAPE_EXTRA, DARCS_ESCAPE_EXTRA, DARCS_DONT_ESCAPE_ISPRINT, and
DARCS_ESCAPE_8BIT
Darcs needs to escape certain characters when printing patch contents to a terminal, depending on the
encoding specified in your locale setting.

By default, darcs assumes that your locale encoding is ASCII compatible. This includes UTF-8 and some
8-bit encodings like ISO/IEC-8859 (including its variants). Since ASCII contains control characters like
backspace (which could hide patch content from the user when printed literally to the terminal), and even
ones that may introduce security risks such as redirecting commands to the shell, darcs needs to escape
such characters. They are printed as `^<control letter>` or `<hex code>`. Darcs also uses special markup
for line endings that are preceeded by white space, since the white space would otherwise not be
recognizable.

If you use an encoding that is not ASCII compatible, things are somewhat less smooth. Such encodings
include UTF-16 and UTF-32, as well as many of the encodings that became obsolete with unicode. In this
case you have two options: you can set DARCS_DONT_ESCAPE_ANYTHING to 1. Then everything that doesn't flip
code sets should work, and so will all the bells and whistles in your terminal. This environment variable
can also be handy if you pipe the output to a pager or external filter that knows better than darcs how
to handle your encoding. Note that all escaping, including the special escaping of any line ending
spaces, will be turned off by this setting.

Another possibility is to explicitly tell darcs to not escape or escape certain bytes, using
DARCS_DONT_ESCAPE_EXTRA and DARCS_ESCAPE_EXTRA. Their values should be strings consisting of the verbatim
bytes in question. The do-escapes take precedence over the dont-escapes. Space characters are still
escaped at line endings though. The special environment variable DARCS_DONT_ESCAPE_TRAILING_CR turns off
escaping of carriage return last on the line (DOS style).

For historical reasons, darcs also supports DARCS_DONT_ESCAPE_ISPRINT and DARCS_USE_ISPRINT (which are
synonyms). These make sense only for 8-bit encodings like ISO-8859 and are no longer needed since
nowadays darcs does the right thing here by default.

Finally, if you are in a highly security sensitive situation (or just paranoid for other reasons), you
can set DARCS_ESCAPE_8BIT to 1. This will cause darcs to escape every non-ASCII byte in addition to ASCII
control characters.

DARCS_TMPDIR and TMPDIR
Darcs often creates temporary directories. For example, the `darcs diff` command creates two for the
working trees to be diffed. By default temporary directories are created in /tmp, or if that doesn't
exist, in _darcs (within the current repo). This can be overridden by specifying some other directory in
the file _darcs/prefs/tmpdir or the environment variable $DARCS_TMPDIR or $TMPDIR.

DARCS_KEEP_TMPDIR
If the environment variable DARCS_KEEP_TMPDIR is defined, darcs will not remove the temporary directories
it creates. This is intended primarily for debugging Darcs itself, but it can also be useful, for
example, to determine why your test preference (see `darcs setpref`) is failing when you run `darcs
record`, but working when run manually.

DARCS_EMAIL and EMAIL
Each patch is attributed to its author, usually by email address (for example, `Fred Bloggs
<fred@example.net>`). Darcs looks in several places for this author string: the `--author` option, the
files `_darcs/prefs/author` (in the repository) and `~/.darcs/author` (in your home directory), and the
environment variables `$DARCS_EMAIL` and `$EMAIL`. If none of those exist, Darcs will prompt you for an
author string and write it to `~/.darcs/author`. Note that if you have more than one email address, you
can put them all in `~/.darcs/author`, one author per line. Darcs will still prompt you for an author,
but it allows you to select from the list, or to type in an alternative.

SENDMAIL
On Unix, the `darcs send` command relies on sendmail(8). The `--sendmail-command` or $SENDMAIL
environment variable can be used to provide an explicit path to this program; otherwise the standard
locations /usr/sbin/sendmail and /usr/lib/sendmail will be tried.

DARCS_SLOPPY_LOCKS
If on some filesystems you get an error of the kind:

darcs: takeLock [...]: atomic_create [...]: unsupported operation

you may want to try to export DARCS_SLOPPY_LOCKS=True.

DARCS_SSH
Repositories of the form [user@]host:[dir] are taken to be remote repositories, which Darcs accesses with
the external program ssh(1).

The environment variable $DARCS_SSH can be used to specify an alternative SSH client. Arguments may be
included, separated by whitespace. The value is not interpreted by a shell, so shell constructs cannot
be used; in particular, it is not possible for the program name to contain whitespace by using quoting or
escaping.

DARCS_SCP and DARCS_SFTP
When reading from a remote repository, Darcs will attempt to run `darcs transfer-mode` on the remote
host. This will fail if the remote host only has Darcs 1 installed, doesn't have Darcs installed at all,
or only allows SFTP.

If transfer-mode fails, Darcs will fall back on scp(1) and sftp(1). The commands invoked can be
customized with the environment variables $DARCS_SCP and $DARCS_SFTP respectively, which behave like
$DARCS_SSH. If the remote end allows only sftp, try setting DARCS_SCP=sftp.

scp is also used by `darcs clone` if the destination is a remote ssh directory. This operation can be
made quite a bit faster by setting DARCS_SCP=rsync.

SSH_PORT
If this environment variable is set, it will be used as the port number for all SSH calls made by Darcs
(when accessing remote repositories over SSH). This is useful if your SSH server does not run on the
default port, and your SSH client does not support ssh_config(5). OpenSSH users will probably prefer to
put something like `Host *.example.net Port 443` into their ~/.ssh/config file.

DARCS_CONNECTION_TIMEOUT
Set the maximum time in seconds that darcs allows and connection to take. If the variable is not
specified the default are 30 seconds. This option only works with curl.

FILES

_darcs/prefs/motd
The `_darcs/prefs/motd` file may contain a 'message of the day' which will be displayed to users who
clone or pull from the repository without the `--quiet` option.

_darcs/prefs/email
The `_darcs/prefs/email` file is used to provide the e-mail address for your repository that others will
use when they `darcs send` a patch back to you. The contents of the file should simply be an e-mail
address.

_darcs/prefs/post
If `_darcs/prefs/post` exists in the target repository, `darcs send ` will upload to the URL contained in
that file, which may either be a `mailto:` URL, or an `http://` URL. In the latter case, the patch is
posted to that URL.

_darcs/prefs/author
The `_darcs/prefs/author` file contains the email address (or name) to be used as the author when patches
are recorded in this repository, e.g. `David Roundy <droundy@abridgegame.org>`. This file overrides the
contents of the environment variables `$DARCS_EMAIL` and `$EMAIL`.

_darcs/prefs/defaults
Default options for darcs commands. Each line of this file has the following form:

COMMAND FLAG VALUE

where `COMMAND` is either the name of the command to which the default applies, or `ALL` to indicate that
the default applies to all commands accepting that flag. The `FLAG` term is the name of the long argument
option with or without the `--`, i.e. `verbose` or `--verbose`. Finally, the `VALUE` option can be
omitted if the flag does not involve a value. If the value has spaces in it, use single quotes, not
double quotes, to surround it. Each line only takes one flag. To set multiple defaults for the same
command (or for `ALL` commands), use multiple lines.

Options listed in the defaults file are just that: defaults. You can override any default on the command
line.

Note that the use of `ALL` easily can have unpredicted consequences, especially if commands in newer
versions of darcs accepts flags that they did not in previous versions. Only use safe flags with `ALL`.

For example, if your system clock is bizarre, you could instruct darcs to always ignore the file
modification times by adding the following line:

ALL ignore-times

There are some options which are meant specifically for use in `_darcs/prefs/defaults`. One of them is
`--disable`. As the name suggests, this option will disable every command that got it as argument. So, if
you are afraid that you could damage your repositories by inadvertent use of a command like amend, add
the following line:

amend disable

A global defaults file can be created with the name `.darcs/defaults` in your home directory. In case of
conflicts, the defaults for a specific repository take precedence.

_darcs/prefs/boring
The `_darcs/prefs/boring` file may contain a list of regular expressions describing files, such as object
files, that you do not expect to add to your project. A newly created repository has a boring file that
includes many common source control, backup, temporary, and compiled files.

You may want to have the boring file under version control. To do this you can use darcs setpref to set
the value 'boringfile' to the name of your desired boring file (e.g. `darcs setpref boringfile .boring`,
where `.boring` is the repository path of a file that has been darcs added to your repository). The
boringfile preference overrides `_darcs/prefs/boring`, so be sure to copy that file to the boringfile.

You can also set up a 'boring' regexps file in your home directory, named `~/.darcs/boring`, which will
be used with all of your darcs repositories.

Any file not already managed by darcs and whose repository path matches any of the boring regular
expressions is considered boring. The boring file is used to filter the files provided to darcs add, to
allow you to use a simple `darcs add newdir newdir/*` without accidentally adding a bunch of object
files. It is also used when the `--look-for-adds` flag is given to whatsnew or record. Note that once a
file has been added to darcs, it is not considered boring, even if it matches the boring file filter.

_darcs/prefs/binaries
The `_darcs/prefs/binaries` file may contain a list of regular expressions describing files that should
be treated as binary files rather than text files. Darcs automatically treats files containing characters
`^Z` or `NULL` within the first 4096 bytes as being binary files. You probably will want to have the
binaries file under version control. To do this you can use `darcs setpref` to set the value
'binariesfile' to the name of your desired binaries file (e.g. `darcs setpref binariesfile ./.binaries`,
where `.binaries` is a file that has been darcs added to your repository). As with the boring file, you
can also set up a `~/.darcs/binaries` file if you like.

_darcs/prefs/defaultrepo
Contains the URL of the default remote repository used by commands `pull`, `push`, `send` and `optimize
relink`. Darcs edits this file automatically or when the flag `--set-default` is used.

_darcs/prefs/sources
Besides the defaultrepo, darcs also keeps track of any other locations used in commands for exchanging
patches (e.g. push, pull, send). These are subsequently used as alternatives from which to download
patches. The file contains lines such as:

cache:/home/droundy/.cache/darcs
readonly:/home/otheruser/.cache/darcs
repo:http://darcs.net

The prefix `cache:` indicates that darcs can use this as a read-write cache for patches, `read-only:`
indicates a cache that is only readable, and `repo:` denotes a (possibly remote) repository. The order of
the entries is immaterial: darcs will always try local paths before remote ones, and only local ones will
be used as potentially writable.

A global cache is enabled by default in your home directory under `.cache/darcs` (older versions of darcs
used `.darcs/cache` for this), or `$XDG_CACHE_HOME/darcs` if the environment variable is set, see
https://specifications.freedesktop.org/basedir-spec/basedir-spec-latest.html. The cache allows darcs to
avoid re-downloading patches (for example, when doing a second darcs clone of the same repository), and
also allows darcs to use hard links to reduce disk usage.

Note that the cache directory should reside on the same filesystem as your repositories, so you may need
to vary this. You can also use multiple cache directories on different filesystems, if you have several
filesystems on which you use darcs.

While darcs automatically adds entries to `_darcs/prefs/sources`, it does not currently remove them. If
one or more of the entries aren't accessible (e.g. because they resided on a removable media), then darcs
will bugger you with a hint, suggesting you remove those entries. This is done because certain systems
have extremely long timeouts associated with some remotely accessible media (e.g. NFS over automounter on
Linux), which can slow down darcs operations considerably. On the other hand, when you clone a repo with
--lazy from a no longer accessible location, then the hint may give you an idea where the patches could
be found, so you can try to restore access to them.

_darcs/prefs/tmpdir
By default temporary directories are created in `/tmp`, or if that doesn't exist, in `_darcs` (within the
current repo). This can be overridden by specifying some other directory in the file
`_darcs/prefs/tmpdir` or the environment variable `$DARCS_TMPDIR` or `$TMPDIR`.

_darcs/prefs/prefs
Contains the preferences set by the command `darcs setprefs`. Do not edit manually.

BUGS

       At http://bugs.darcs.net/ you can find a list of known bugs in Darcs.  Unknown bugs can  be  reported  at
       that site (after creating an account) or by emailing the report to bugs@darcs.net.

LICENSE

       Darcs  is  free  software;  you  can  redistribute it and/or modify it under the terms of the GNU General
       Public License as published by the Free Software Foundation; either version 2, or (at  your  option)  any
       later version.

                                                2.18.4 (release)                                        DARCS(1)