#pragma section-numbers 2 <> = Tag = (''Note: If you are migrating from CVS, please [[CvsConcepts#tag|read this discussion of CVS tags]] before you continue.'') `hg tags`<
> `hg tag [-l] [-m TEXT] [-d DATE] [-u USER] [-r REV] NAME...` A '''tag''' is a symbolic identifier for a [[ChangeSet|changeset]]. It can contain any characters except ":" (colon), "\r" (Carriage Return) or "\n" (Line Feed). Mercurial has two kinds of tags: local and regular. A ''local'' tag is a convenience identifier that is not revision controlled, does not propagate with other changes, and lives in the {{{.hg/localtags}}} file in a [[Repository|repository]]. A "regular" tag (with no special specifier) ''is'' revision controlled, ''does'' propagate with other changes, and lives in the {{{.hgtags}}} file in a repository. <> == Example == {{{ hg tag this_is_my_tag }}} == How do tags work in Mercurial? == Tags work slightly differently in Mercurial than most revision systems. The [[TagDesign|design]] attempts to meet the following requirements: * be version controlled and [[Merge|mergeable]] just like any other file * allow signing of tags * allow adding a tag to an already committed changeset * allow changing tags in the future Thus Mercurial stores tags as a file in the [[WorkingDirectory|working dir]]. This file is called .hgtags and consists of a list of [[ChangeSetID|changeset IDs]] and their corresponding tags. To add a tag to the system, simply add a line to this file and then commit it for it to take effect. The {{{hg tag}}} command will do this for you and {{{hg tags}}} will show the currently effective tags. Note that because tags refer to changeset IDs and the changeset ID is effectively the sum of all the contents of the repository for that change, it is impossible in Mercurial to simultaneously commit and add a tag for the changeset being committed. Thus tagging a revision must be done as a second step. Thus, as above, the only changesets that can be tagged are ones already committed. The fact that tags identify changesets and are also parts of changesets has some potentially confusing implications: * The changeset that a tag refers to is always older than the changeset that commits the tag itself. * [[Update|Updating]] a working dir to a particular tag will take that directory back to a point before the tag itself existed. * Cloning a repo to a particular tag will give you a new repo that does ''not'' have that tag. Common wisdom says that to avoid the confusion of a disappearing tag, you should clone the entire repo and then update the working directory to the tag. Thus preserving the tag in the repo. == What if I want to just keep local tags? == You can use "hg tag" command with an option {{{-l}}} or {{{--local}}}. This will store the tag in the file .hg/localtags, which will not be distributed or versioned. The format of this file is identical to the one of .hgtags and the tags stored there are handled the same. == My tags had a conflict when I was merging. Why? How should I merge them? == Different sets of tags, coming from different branches and heads, can lead to a merge conflict. While Mercurial knows how to handle different {{{.hgtags}}} in different heads, it does not use that knowledge when attempting to merge. Instead, the {{{.hgtags}}} files are merged just like any other file, which can result in file conflicts, even though the resolution is clear. In case of a merge conflict on your tags, the safest option is to take both sides. === How do tags work with multiple heads? === The tags that are in effect at any given time are the tags specified in each [[Head|head]]. A difficult case arises, if the same tag specifies two different revisions in two different heads. There is no general "correct" solution to this problem. If two definitions/changes of tags seem unrelated like in the following diagram, the "[[Tip|tip]]most" (e.g. the one with the higher numeric revision number) wins. {{{#!dot digraph G { "..." -> "Rev: 12" -> "Rev: 13\ntag_a=1" "Rev: 12" -> "Rev: 14\ntag_a=2" } }}} In the above diagram {{{tag_a}}} refers to revision 2, since revision 14 is higher than revision 13. /!\ Note that the numeric revision number depends on the sequence by which changes got pulled into a repository and may therefore vary even on repositories containing the same changesets. However if a tag was defined in a common ancestor of both heads, but changed in just one head, the changed one wins over the unchanged one. {{{#!dot digraph G { "..." -> "Rev: 12\ntag_b=9" -> "Rev: 13\ntag_b=10" "Rev: 12\ntag_b=9" -> "Rev: 14\n (this revision still contains tag_b=9) " } }}} In the above diagram {{{tag_b}}} revers to revision 10, although revision 13 is not tip. /!\ Note that this ''multiple-head tag collision resolution algorithm'' depends on the {{{.hgtags}}}-file to be append only and be carefully merged. Local tags override all other tags. See also: [[MultipleHeads]] == What if multiple lines with different revisions use the same tag name in .hgtags? == If there is just one head only the last line where the tag appears is taken into account. If there are multiple heads, the previous definitions of the tag are used to determine which head holds the most recent tag. See "How do tags work with multiple heads?". If a tag points to {{{0000000000000000000000000000000000000000}}} it is considered to be deleted. The behavior is identical when this happens in .hg/localtags. == How do I remove a tag? == Either by * {{{hg tag --remove tagname}}} (this being the nearest equivalent to {{{cvs tag -d}}}) * adding {{{tagname 0000000000000000000000000000000000000000}}} to the end of {{{.hgtags}}} * removing all references to ''tagname'' in {{{.hgtags}}} (but this might confuse the multiple-head tag collision resolution algorithm) == See Also == * TagDesign * http://www.selenic.com/mercurial/hg.1.html#tag * http://www.selenic.com/mercurial/hg.1.html#tags ---- CategoryCommand CategoryGlossary [[FrenchTag|Français]]