$ gf build
2020-12-31 00:35:25.562 start building...
2020-12-31 00:35:25.562 go build -o ./bin/darwin_amd64/gf main.go
2020-12-31 00:35:28.381 go build -o ./bin/freebsd_386/gf main.go
2020-12-31 00:35:30.650 go build -o ./bin/freebsd_amd64/gf main.go
2020-12-31 00:35:32.957 go build -o ./bin/freebsd_arm/gf main.go
2020-12-31 00:35:35.824 go build -o ./bin/linux_386/gf main.go
2020-12-31 00:35:38.082 go build -o ./bin/linux_amd64/gf main.go
2020-12-31 00:35:41.076 go build -o ./bin/linux_arm/gf main.go
2020-12-31 00:35:44.369 go build -o ./bin/linux_arm64/gf main.go
2020-12-31 00:35:47.352 go build -o ./bin/linux_ppc64/gf main.go
2020-12-31 00:35:50.293 go build -o ./bin/linux_ppc64le/gf main.go
2020-12-31 00:35:53.166 go build -o ./bin/linux_mips/gf main.go
2020-12-31 00:35:55.840 go build -o ./bin/linux_mipsle/gf main.go
2020-12-31 00:35:58.423 go build -o ./bin/linux_mips64/gf main.go
2020-12-31 00:36:01.062 go build -o ./bin/linux_mips64le/gf main.go
2020-12-31 00:36:03.502 go build -o ./bin/netbsd_386/gf main.go
2020-12-31 00:36:06.280 go build -o ./bin/netbsd_amd64/gf main.go
2020-12-31 00:36:09.332 go build -o ./bin/netbsd_arm/gf main.go
2020-12-31 00:36:11.811 go build -o ./bin/openbsd_386/gf main.go
2020-12-31 00:36:14.140 go build -o ./bin/openbsd_amd64/gf main.go
2020-12-31 00:36:17.859 go build -o ./bin/openbsd_arm/gf main.go
2020-12-31 00:36:20.327 go build -o ./bin/windows_386/gf.exe main.go
2020-12-31 00:36:22.994 go build -o ./bin/windows_amd64/gf.exe main.go
2020-12-31 00:36:25.795 done!