`os.execute` in LuaTeX behaves as that in Lua 5.1

[muzimuzhi]

Till Lua 5.1, os.execute returns a single result. Starting from Lua 5.2, it returns three results.

Although LuaTeX (v1.21, Feb 2025) uses Lua 5.3, it's os.execute still behaves like that in Lua 5.1. Unfortunately this is not documented in the LuaTeX manual.

See latex3/l3build#333 for more info.

I found a related mailing list thread https://tug.org/pipermail/luatex/2015-November/005536.html .

Update: From the latest reimplementation of os.execute in LuaTeX source (in order to take shell-escape state into account), yes os.execute provided by LuaTeX still returns a single result.

(Updated link to the reimplementation of os.execute in LuaTeX)

Is it possible to overwrite the signature of a Lua builtin function?

[Josef-Friedrich]

Thank you for reporting this

Yes that is possible

The corresponding links in the LuaTeX repo

https://gitlab.lisn.upsaclay.fr/texlive/luatex/-/blob/f52b099f3e01d53dc03b315e1909245c3d5418d3/source/texk/web2c/luatexdir/lua/loslibext.c#L1080

https://gitlab.lisn.upsaclay.fr/texlive/luatex/-/blob/f52b099f3e01d53dc03b315e1909245c3d5418d3/source/texk/web2c/luatexdir/lua/loslibext.c#L1000-1047