hg commit is a fundamental command in Mercurial, a distributed version control system, used to save changes made to files in a repository. When developers make modifications to files in their working directory and want to permanently record these changes in the repository’s history, they use the hg commit command. Here’s a detailed explanation of hg commit:
- Recording Changes: The primary function of hg commit is to record changes made to files in the repository. Before committing, developers typically stage their changes using hg add or hg remove to specify which files should be included in the commit.
- Staging Area: Mercurial uses a staging area known as the “commit queue” to manage changes before they are committed. When a file is modified, Mercurial places it in the commit queue, where developers can review and selectively include or exclude changes from the next commit using commands like hg add and hg forget.
- Commit Message: Every commit in Mercurial is accompanied by a commit message, which provides a concise description of the changes being committed. When invoking hg commit, developers are prompted to enter a commit message using their default text editor or a specified editor. This message should accurately describe the purpose and context of the changes.
- Revision History: Once committed, the changes become part of the repository’s revision history. Each commit creates a new changeset that encapsulates the modifications made to files at that point in time. Developers can view the revision history using commands like hg log to see a chronological list of commits and their associated metadata.
- Atomic Operation: In Mercurial, committing changes is an atomic operation, meaning that either all staged changes are successfully committed, or none of them are. This ensures that the repository remains in a consistent state and prevents partial commits that could lead to inconsistencies.
- Documentation Reference: The Mercurial documentation provides comprehensive information about the hg commit command, including usage examples, options, and best practices for writing informative commit messages. Developers can refer to this documentation to learn more about committing changes effectively and efficiently.
“hg commit” Command Examples
1. Commit staged files to the repository:
# hg commit
2. Commit a specific file or directory:
# hg commit [path/to/file_or_directory]
3. Commit with a specific message:
# hg commit --message [message]
4. Commit all files matching a specified pattern:
# hg commit --include [pattern]
5. Commit all files, excluding those that match a specified pattern:
# hg commit --exclude [pattern]
6. Commit using the interactive mode:
# hg commit --interactive
Summary
In summary, hg commit is a crucial command in Mercurial for recording changes made to files in a repository. By using this command judiciously and providing clear and descriptive commit messages, developers can maintain a well-documented revision history and collaborate effectively on software projects.