Is there a way to tell GHC to dump all warnings to a file?

Question

I've tried the following so far:

me@pc:~/code$ ghc file.hs -Wall | tee warnings.log
me@pc:~/code$ ghc file.hs -Wall > warnings.log

But ghc just prints the warnings like normal and only passes on the non-warning steps.

Is there a way to do this?

Answer 1

The reason why it still shows these warnings is because warnings and errors are printed on the standard error channel (stderr).

You can thus redirect the errors to a file by redirecting the stderr, with:

ghc file.hs -Wall  warnings.log

Notice the 2 in > . > 。 As said before, both the warnings and the exceptions are printed to this channel.

We can redirect the error stream to tee in bash with:

ghc -Wall file.hs 

this features works for bash , but as far as I know, this is not defined in the POSIX standard. For bash this works, but for sh , this seems to fail.