4.4. Help and verbosity options
- ––help, -?
Cause GHC to spew a long usage message to standard output and then exit.
- -v
The -v option makes GHC verbose: it reports its version number and shows (on stderr) exactly how it invokes each phase of the compilation system. Moreover, it passes the -v flag to most phases; each reports its version number (and possibly some other information).
Please, oh please, use the -v option when reporting bugs! Knowing that you ran the right bits in the right order is always the first thing we want to verify.
- -vn
To provide more control over the compiler's verbosity, the -v flag takes an optional numeric argument. Specifying -v on its own is equivalent to -v3, and the other levels have the following meanings:
- -v0
Disable all non-essential messages (this is the default).
- -v1
Minimal verbosity: print one line per compilation (this is the default when ––make or ––interactive is on).
- -v2
Print the name of each compilation phase as it is executed. (equivalent to -dshow-passes).
- -v3
The same as -v2, except that in addition the full command line (if appropriate) for each compilation phase is also printed.
- -v4
The same as -v3 except that the intermediate program representation after each compilation phase is also printed (excluding preprocessed and C/assembly files).
- ––version
Print a one-line string including GHC's version number.
- ––numeric-version
Print GHC's numeric version number only.
- ––print-libdir
Print the path to GHC's library directory. This is the top of the directory tree containing GHC's libraries, interfaces, and include files (usually something like /usr/local/lib/ghc-5.04 on Unix). This is the value of $libdirin the package configuration file (see Section 4.10).