[Tex/LaTex] Inserting git commit date without hooks

gitpackagesrevision control

Is there a way to insert the last git commit date into a document without having to add git hooks (like the gitinfo package does it)?

I'm not 100% sure how LaTeX packages work, but if they can access the current directory during compile-time and if they can execute external commands, that should easily be possible…

Best Answer

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This is svn but any command line is the same.

Depending on your configuration you probably need

pdflatex --enable-write18 filename

to enable \write18 to be a hook to execute shell commands.

this writes to a temporary file using the shell escape, then inputs it

\documentclass{article}

\begin{document}

\immediate\write18{svn info \jobname.tex | grep "Changed Date" > \jobname.info }
\fbox{\input{\jobname.info}}

\end{document}

Related Solutions

[Tex/LaTex] Using TeXstudio and git to automatically commit using the current date

I found a solution to this problem with the following steps:

Create a batch file in the directory of your main *.tex file
Open the batch file and add the following line: git commit -am "autosave %date%-%time:~0,8%". This will commit all changes made (-a switch) and set the commit message to e.g. autosave 2015-08-17-09:34:05
Add a custom command in TeXstudio that executes your batch script (see image below for an example)
Add your custom command to the list of commands for compilation
After the next compilation of the document, the following message will appear in the message log:
Additionally, the batch file could be modified accordingly to push the changes directly to the remote repository via git push

[Tex/LaTex] How to include the current Git commit ID and branch in the document

As stated in the question, the branch name can be extracted from .git/HEAD and given [branch name], the commit ID can be found in .git/refs/heads/[branch name].

The package catchfile provides the command \CatchFileDef, which allows us to read .git/HEAD into a macro. As HEAD has no file extension, MiKTeX users have to add a trailing dot to the file name:

\CatchFileDef{\headfull}{.git/HEAD.}{}

This assigns something like ref: refs/heads/master to \headfull. As this string has a trailing whitespace character, we use \StrGobbleRight from the xstring package to trim it:¹

\StrGobbleRight{\headfull}{1}[\head]

In order to extract only the branch name (master in the example) from this string, we can use \StrBehind:

\StrBehind[2]{\head}{/}[\branch]

This saves the branch name in \branch. Finally, we can use \CatchFileDef again, to save the commit ID in \commit:

\CatchFileDef{\commit}{.git/refs/heads/\branch.}{}

There are some edge cases where .git/refs/heads/\branch. does not exist: After running git pack-refs (which is a side effect of git gc --aggressive, for example), the heads are packed into the file .git/packed-refs instead of individual branchname files. As a workaround, check if the file exists before trying to read it:

\IfFileExists{.git/refs/heads/\branch.}{%
    \CatchFileDef{\commit}{.git/refs/heads/\branch.}{}}{%
    \newcommand{\commit}{\dots~(in \emph{packed-refs})}}

As a fallback, this creates the (not-so-useful) output "... (in packed-refs)" instead of a commit ID – but this only lasts until the next commit, when the file heads/branchname is recreated for the affected branch. (A more ambitious workaround could parse packed-refs, of course.)

Full MWE:

\documentclass{article}

\usepackage{xstring}
\usepackage{catchfile}

\CatchFileDef{\headfull}{.git/HEAD.}{}
\StrGobbleRight{\headfull}{1}[\head]
\StrBehind[2]{\head}{/}[\branch]
\IfFileExists{.git/refs/heads/\branch.}{%
    \CatchFileDef{\commit}{.git/refs/heads/\branch.}{}}{%
    \newcommand{\commit}{\dots~(in \emph{packed-refs})}}

\begin{document}
This revision: \texttt{\commit} on branch \texttt{\branch}.
\end{document}

Sample output:

This revision: d92dc1386e48e04ceecb85461ed3b232146e6a32 on branch master.

¹ Using the last optional argument of \StrGobbleRight (name) to assign the trimmed string to a macro (\head) is necessary to allow further manipulation of the string using the xstring functions – see here for a discussion.