Update README with better instructions

README.md

@@ -3,4 +3,28 @@
 ![](logo.png)
 
 `gonix` is a UNIX Operating System (based on the Linux Kernel) with a Userland mostly written in [Go](https://golang.org)
-including Networking, Services, Device Management and an integrated SSH service.
+including Networking, Services, Device Management and an integrated SSH service.
+
+![](./screenshot.png)
+
+## Quick Start
+
+Building GoNix rrquires [Docker](https://docker.com):
+
+```#!sh
+$ docker build -t builder .
+$ docker run -i -t --rm -v $PWD/artefacts:/build/artefacts builder
+```
+
+A `boot.iso` should have been created which can be booted on any x86 system
+such as VirtualBox, QEMU or _any_ Cloud Provider.
+
+Running GoNix in QEMU:
+
+```#!sh
+./test.sh
+```
+
+## License
+
+GoNix is licensed under the terms of the [MIT License](/LICENSE)

cmd/coreutils/applets.go

@@ -31,6 +31,7 @@ import (
 	_ "git.mills.io/prologic/gonix/internal/applets/expand"
 	_ "git.mills.io/prologic/gonix/internal/applets/factor"
 	_ "git.mills.io/prologic/gonix/internal/applets/false"
+	_ "git.mills.io/prologic/gonix/internal/applets/free"
 	_ "git.mills.io/prologic/gonix/internal/applets/grep"
 	_ "git.mills.io/prologic/gonix/internal/applets/groups"
 	_ "git.mills.io/prologic/gonix/internal/applets/gunzip"
@@ -72,7 +73,6 @@ import (
 	_ "git.mills.io/prologic/gonix/internal/applets/shuf"
 	_ "git.mills.io/prologic/gonix/internal/applets/sleep"
 	_ "git.mills.io/prologic/gonix/internal/applets/sync"
-	_ "git.mills.io/prologic/gonix/internal/applets/sysinfo"
 	_ "git.mills.io/prologic/gonix/internal/applets/tac"
 	_ "git.mills.io/prologic/gonix/internal/applets/tail"
 	_ "git.mills.io/prologic/gonix/internal/applets/tau"

internal/applets/free/free.go

@@ -0,0 +1,162 @@
+package free
+
+import (
+	"flag"
+	"fmt"
+	"io"
+
+	"git.mills.io/prologic/gonix/internal/applets"
+	"git.mills.io/prologic/gonix/internal/common"
+	"github.com/dustin/go-humanize"
+)
+
+const binaryName = "free"
+
+const helpText = `
+Display the amount of free and used system memory
+`
+
+type unit uint
+
+const (
+	// B is bytes
+	B unit = 0
+	// KB is kibibytes
+	KB = 10
+	// MB is mebibytes
+	MB = 20
+	// GB is gibibytes
+	GB = 30
+	// TB is tebibytes
+	TB = 40
+)
+
+var units = [...]string{"B", "K", "M", "G", "T"}
+
+type Config struct {
+	Unit        unit
+	HumanOutput bool
+}
+
+func init() {
+	applets.Register(binaryName, Main)
+}
+
+type Option struct {
+	helpFlag bool
+	hFlag    bool
+	bFlag    bool
+	kFlag    bool
+	mFlag    bool
+	gFlag    bool
+}
+
+// Validate checks that only one option of -b, -k, -m, -g or -h has been
+// specified on the command line
+func (opt *Option) Validate() bool {
+	count := 0
+	if opt.bFlag {
+		count++
+	}
+	if opt.kFlag {
+		count++
+	}
+	if opt.mFlag {
+		count++
+	}
+	if opt.gFlag {
+		count++
+	}
+	if opt.hFlag {
+		count++
+	}
+	if count > 1 {
+		return false
+	}
+	return true
+}
+
+func NewFlagSet() (*flag.FlagSet, *Option) {
+	ret := flag.NewFlagSet(binaryName, flag.ExitOnError)
+
+	ret.Usage = func() {
+		fmt.Printf("Usage: %s [OPTIONS] ...\n", binaryName)
+		fmt.Printf("%s\n", helpText)
+		ret.PrintDefaults()
+	}
+
+	var opt Option
+
+	ret.BoolVar(&opt.helpFlag, "help", false, "show this message")
+	ret.BoolVar(&opt.hFlag, "h", false, "Display values in human readable form")
+	ret.BoolVar(&opt.bFlag, "b", false, "Display values in bytes")
+	ret.BoolVar(&opt.kFlag, "k", false, "Display values in kitobytes")
+	ret.BoolVar(&opt.mFlag, "m", false, "Display values in megabytes")
+	ret.BoolVar(&opt.gFlag, "g", false, "Display values in gigabytes")
+
+	return ret, &opt
+}
+
+func Main(stdout io.Writer, args []string) error {
+	flagSet, opt := NewFlagSet()
+	flagSet.Parse(args)
+
+	if opt.helpFlag {
+		flagSet.Usage()
+		return nil
+	}
+
+	return free(stdout, flagSet.Args(), opt)
+}
+
+// formatValueByConfig formats a size in bytes in the appropriate unit,
+// depending on whether FreeConfig specifies a human-readable format or a
+// specific unit
+func formatValueByConfig(value uint64, config *Config) string {
+	if config.HumanOutput {
+		return humanize.Bytes(value)
+	}
+	// units and decimal part are not printed when a unit is explicitly specified
+	return fmt.Sprintf("%v", value>>config.Unit)
+}
+
+func free(w io.Writer, args []string, opt *Option) error {
+	if !opt.Validate() {
+		return fmt.Errorf("options -k, -m, -g and -h are mutually exclusive")
+	}
+
+	config := &Config{HumanOutput: opt.hFlag}
+
+	switch {
+	case opt.bFlag:
+		config.Unit = B
+	case opt.kFlag:
+		config.Unit = KB
+	case opt.mFlag:
+		config.Unit = MB
+	case opt.gFlag:
+		config.Unit = GB
+	}
+
+	sysinfo, err := common.Sysinfo()
+	if err != nil {
+		return err
+	}
+
+	fmt.Fprintf(w, "              total        used        free      shared     buffers\n")
+	fmt.Fprintf(w, "%-7s %11v %11v %11v %11v %11v\n",
+		"Mem:",
+		formatValueByConfig(sysinfo.TotalRam, config),
+		formatValueByConfig(sysinfo.TotalRam-sysinfo.FreeRam, config),
+		formatValueByConfig(sysinfo.FreeRam, config),
+		formatValueByConfig(sysinfo.SharedRam, config),
+		formatValueByConfig(sysinfo.BufferRam, config),
+	)
+	fmt.Fprintf(w, "%-7s %11v %11v %11v\n",
+		"Swap:",
+		formatValueByConfig(sysinfo.TotalSwap, config),
+		formatValueByConfig(sysinfo.TotalSwap-sysinfo.FreeSwap, config),
+		formatValueByConfig(sysinfo.FreeSwap, config),
+	)
+	return nil
+}

internal/applets/sysinfo/sysinfo.go

@@ -1,56 +0,0 @@
-package sysinfo
-
-import (
-	"flag"
-	"fmt"
-	"io"
-
-	"git.mills.io/prologic/gonix/internal/applets"
-	"git.mills.io/prologic/gonix/internal/common"
-)
-
-const binaryName = "sysinfo"
-
-func init() {
-	applets.Register(binaryName, Main)
-}
-
-var (
-	help bool
-)
-
-func NewFlagSet() *flag.FlagSet {
-	ret := flag.NewFlagSet(binaryName, flag.ExitOnError)
-
-	ret.Usage = func() {
-		fmt.Println("sysinfo [OPTIONS]")
-		ret.PrintDefaults()
-	}
-
-	ret.BoolVar(&help, "help", false, "show this message")
-
-	return ret
-}
-
-func Main(stdout io.Writer, args []string) error {
-	flagSet := NewFlagSet()
-	flagSet.Parse(args)
-
-	if help {
-		flagSet.Usage()
-		return nil
-	}
-
-	return sysinfo(stdout, flagSet.Args())
-}
-
-func sysinfo(w io.Writer, args []string) error {
-	sysinfo, err := common.Sysinfo()
-	if err != nil {
-		return err
-	}
-
-	fmt.Fprintln(w, sysinfo.String())
-
-	return nil
-}