I would like to parse the latex log to extract warnings from the refcheck package. These warnings look like this

Package refcheck Warning: Unused label `eq:my_equation_label' on input line 2

The linebreak always appears after a given number of characters, and here it happens to break the line number. I have been trying to set up a working errorformat for a couple of hours but this was to no avail. Any idea how I could extract the correct error message and line number?

  • 2
    I'm not an expert of errorFormat but I think if you shared what you have done so far, maybe it could be easier for other users to point out what doesn't work with your expression.
    – statox
    Mar 15, 2019 at 22:14

1 Answer 1


Afaik 'efm' of vim cannot handle this situation, i.e. %l matches only a sequence of digits with no spaces or linebreaks between the digits. Vim help discusses in more detail a possible value of'efm' for LaTeX but does not answer this question:

:help errorformat-LaTeX

Maybe you can ask this on the issue tracker of vim or the vim_dev mailing list to get an official confirmation of this and possibly add a note to the vim help section.

However, there are two ways to handle it anyway:

  1. Change the line length of the log output of pdflatex to a high value. For example, set makeprg in vim as following:

    :set makeprg=max_print_line=10000\ pdflatex\ %

    Also the plugin vimtex does this for the default compilation method with latexmk and would show you also the message by default.

  2. Post-process the log file with an external tool, e.g. rubber-info correctly parses the splitted line number. The principle idea is

    :set mp=pdflatex\ %\ \\\|&\ error_filter

    For LaTeX log files quite a few tools exist. Following two are pre-installed under TeXLive 2018

    However, both struggle with the linebreak in the line number and report the wrong line number.

    I have tried following further tools

    • pplatex gets the line number correct but does not capture the full message. The warning

      Package refcheck Warning: Unused label `eq:your_equation_label' on input line 1

      is converted by pplatex to:

      ** Warning in ./demo-multine-efm.tex:
         (Package refcheck) your_equation_label' on input line 17.
    • rubber-info was successful

      WARNING:rubber.cmdline:demo-multine-efm.tex:17: [refcheck] Unused label `eq:your_equation_label'. (page 1)

    Other tools are

Demo file



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Running latex returns a refcheck warning with a line number containing a linebreak (1\n2):

❯ latex log-msg-line-no-with-linebreak.tex
This is pdfTeX, Version 3.14159265-2.6-1.40.19 (TeX Live 2018) (preloaded format=latex)
 restricted \write18 enabled.
entering extended mode
LaTeX2e <2018-12-01>
Document Class: article 2018/09/03 v1.4i Standard LaTeX document class
No file log-msg-line-no-with-linebreak.aux.
Package: `refcheck' v1.9.1 <2013/02/14>
options: showrefs, showcites, msgs, chckunlbld

Package refcheck Warning: Unused label `eq:your_equation_label' on input line 1

[1] (./log-msg-line-no-with-linebreak.aux)

LaTeX Warning: Label(s) may have changed. Rerun to get cross-references right.

Output written on log-msg-line-no-with-linebreak.dvi (1 page, 816 bytes).
Transcript written on log-msg-line-no-with-linebreak.log.


:set efm=%+WPackage\ %s\ Warning:\ %m\ on\ input\ line\ %l

reading the log file manually :cfile log-msg-line-no-with-linebreak.log generates following warning:

|1 warning| Package refcheck Warning: Unused label `eq:your_equation_label' on input line 1

As you can see the warning is issued for line number 1 which is incorrect.

For the purpose of reference I want to add links to 'efm' settings for latex or external tools

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