1

I got a LaTeX project that has been exported (downloaded) from an ShareLaTeX Online installation. Seems that it stored all Tex files as US-ASCII according to what I see on MacOS using the following command in the terminal:

file -I myfile.tex

Which results in:

myfile.tex: text/x-tex; charset=us-ascii

The original error is:

myfile.tex:8: Undefined control sequence. ...\numberline {\thechapter }Vortr\UTF{00E4}ge}{\thepage }} l.8 \chapter{Vortr\UTF{00E4}ge}

And the LaTeX source is (where the \ got copied and pasted here as a ¥ symbol). The original file can be download here.

\documentclass[12pt,a4paper,ngerman,onecolumn]{book}
\usepackage[ngerman,english]{babel}  
\usepackage[T1]{fontenc}
\usepackage[utf8]{inputenc}

\begin{document}

\chapter{Vorträge}

\end{document}

The question is, can I fix this somehow? I know that UTF-8 is the better choice. But the LaTeX project consists of many files that are all in the US-ASCII encoding.

  • 1
    Well, LaTeX is right. You say inputenc that your files are utf8 encoded. That has to be changed. – TeXnician Jul 24 '17 at 18:15
  • Changed to which argument instead? – Matthias Jul 24 '17 at 18:15
  • ascii according to the manual. And make sure to delete auxiliary files. – TeXnician Jul 24 '17 at 18:19
  • Hmm, I tried removing the encoding since the ASCII encoding is the default one. And I tried replacing utf8 by ascii, but still both options didn't work. Maybe I will just re-create all files in UTF-8 encoding. – Matthias Jul 24 '17 at 18:23
  • 3
    ASCII is a 7-bit encoding that does not have accented characters, so whatever encoding your file is in, it isn't ASCII. – David Carlisle Jul 24 '17 at 18:36
3

The exported file has replaced the UTF-8 characters by macro calls \UTF{...} with the hexadecimal Unicode code point as argument. The macro could be defined in TeX, but this will not work in all circumstances (verbatim text, ...). Therefore, the best approach is to write a script/program to convert the macro calls back to the UTF-8 encoded Unicode characters.

Here a simple script sharelatex_recode.py for Python 3. It takes the file as argument and updates the file if necessary:

#!/usr/bin/env python

import argparse
import re
import sys

if sys.version_info[0:2] < (3, 2):  # tested with 3.6
    print('Python >= 3.2 is required.')
    sys.exit(1)


def main():
    args = parse_command_line()
    convert(args.input_file, args.dry_run)


def parse_command_line():
    parser = argparse.ArgumentParser(
        description=r'Replace TeX macro \UTF{...} calls to UTF-8 characters.',
    )
    parser.add_argument(
        'input_file',
        help='input TeX file',
    )
    parser.add_argument(
        '--dry-run',
        action='store_true',
        help='the file is not updated and written',
    )
    return parser.parse_args()


def convert(file_name, dry_run):
    with open(file_name, 'rb') as handle:
        data = handle.read()

    new_data, replacements = re.subn(
        br'\\UTF\{([0-9A-Fa-f]{4})\}',
        repl,
        data,
    )

    if replacements:
        print('=> Replacements: {}'.format(replacements))
        if not dry_run:
            with open(file_name, 'wb') as handle:
                handle.write(new_data)

            print('=> File written: {}'.format(file_name))
    else:
        print('=> Already uptodate: {}'.format(file_name))


def repl(match):
    code = int(match.group(1), 16)
    char = chr(code)
    utf8_sequence = char.encode('utf8')
    return utf8_sequence


if __name__ == '__main__':
    main()

The problematic line

\chapter{Vortr\UTF{00E4}ge}

becomes

\chapter{Vorträge}

It is also possible to convert all .tex files recursively, example for bash:

$ find start_directory -name \*.tex -exec python3 sharelatex_recode.py {} \;

Unicode characters outside the BMP (Basic Multilingual Plane) are not supported by the script, because I do not know, what the export of ShareLaTeX to US ASCII does in this case.

  • Executing the script worked like a charm. But still there are errors. If I remove \usepackage[utf8]{inputenc}, then the output will be VortrÃďge. If I add the encoding again, then the file won't compile. But looks like a TexShop problem even though it's set to UTF-8 encoding when saving files. But the original file isn't UTF-8. Weird. – Matthias Jul 28 '17 at 9:09
  • Seemed to be a problem of the auxillery files. Works perfectly now. Thanks for your help. – Matthias Jul 28 '17 at 9:20

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