Replace LaTeX with $ and multi-line

Question

I want to use sed to replace something like $some latex$ or

$$
some latex
$$

with {% math %}some latex {% endmath %} or

{% math %}
some latex
{% endmath %}

I try sed to solve this problem but a command like

sed -e 's/\$\([^\$]\{1,\}\)\$/{% math %}\1{% endmath %}/g' filename

doesn't work for $some latex$ and I don't know how to deal with multi-line. How can I do this?

Answer 1

The only problem you are facing here is capturing newline or whitespace , which is solved by following regex.

Regex: (?:\\$*)(\\s*)some latex(\\s*)(?:\\$*)

Flags used:

• g for global search.

Explanation:

• (?:\\$*)(\\s*) captures the whitespace or newline after leading $ or $$

• (\\s*)(?:\\$*) captures the whitespace or newline before trailing $ or $$

Replacement to do: {% math %}\\1some latex\\2{% endmath %}

Regex101 Demo

Answer 2

Try this with sed :

sed -e ' /\$\$/{s/\$\$/{% math %}/;:a;N;/\$\$/!ba;s/\$\$/{% endmath %}/};s/^\(\$\)\(.*\)\(\$\)$/{% math %}\2{% endmath %}/' sourcefile

Multiline is preserved.

Update :

It seems there is a BSD (OS X?) sed issue with semi colons .

It should work replacing it with new lines :

sed -e '
  /\$\$/ {
    s/\$\$/{% math %}/
      :a
      N
      /\$\$/!ba
      s/\$\$/{% endmath %}/;}
      s/^\(\$\)\(.*\)\(\$\)$/{% math %}\2{% endmath %}/
' sourcefile

I also updated the last s command to match lines like $ \\$ $ mentioned in you comments.