ghdl
Open-source simulator for the VHDL language.
TLDR
Analyze a VHDL source file and produce an object file
$ ghdl -a [filename.vhdl]
Elaborate a design (where {{design}} is the name of a configuration unit, entity unit or architecture unit)
$ ghdl -e [design]
Run an elaborated design
$ ghdl -r [design]
Run an elaborated design and dump output to a waveform file
$ ghdl -r [design] --wave=[output.ghw]
Check the syntax of a VHDL source file
$ ghdl -s [filename.vhdl]
Display the help page
$ ghdl --help