Know what flags were used with configure script after compiling

Question

Let's say I'm compiling some application (codebase in C, using gcc as default compiler, git cloned from github...) and doing ./configure --flags1 --flags2 ...

And after compiling finish, i want to know the flags i used on ./configure (in this hypothetical case, i can't know that by looking in my shell history as it is lost).

The flags list could be pretty long, and i wouldn't want to waste time hunting down those said flags (especially since some could not be documented in the previously mentioned application).

Any ways to know the flags that were used for a compiled application? maybe by looking at whatever files ./configure generate?

score 1 · Accepted Answer · answered Sep 24 '20 at 19:53

1

They're in the config.log:

head -n8 config.log
This file contains any messages produced by compilers while
running configure, to aid debugging if configure makes a mistake.
It was created by configure, which was
generated by GNU Autoconf 2.52.20190901.  Invocation command line was
$ ./configure --enable-trace

You can easily parse that with a bit of sed from the Makefile and include that info as a string in your binary. I don't know if any other program does that, though ;-)

answered Sep 24 '20 at 19:53

this is it! yeah, i only wanted to know that specifically for ./configure :P so that should work on most cases i think. – Nordine Lotfi Sep 24 '20 at 19:55
gcc does that... gcc -v – rfmodulator Sep 24 '20 at 19:59
yeah, most compilers support this afaik (99% of them, not sure of the one that are arcane/rare enough) @rfmodulator – Nordine Lotfi Sep 24 '20 at 20:00

Know what flags were used with configure script after compiling

1 Answers1