commit f7443bbab911d33df7d264ff03c5bf614dbc1644
Author: Geir Okkenhaug Jerstad <geokkjer@gmail.com>
Date:   Tue Aug 13 20:31:39 2024 +0200

    init

diff --git a/#echo1.go# b/#echo1.go#
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--- /dev/null
+++ b/#echo1.go#
@@ -0,0 +1,16 @@
+// Echo1 prints its command-line arguments.
+package main
+
+import (
+	"fmt"
+	"os"
+)
+
+func main() {
+	var s, sep string
+	for i := 1;i < len(os.Args); i++ {
+		s += sep + os.Args[i]
+		sep = " "
+	}
+	fmt.Println(s)
+}
diff --git a/.envrc b/.envrc
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--- /dev/null
+++ b/.envrc
@@ -0,0 +1 @@
+use nix 
diff --git a/default.nix b/default.nix
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--- /dev/null
+++ b/default.nix
@@ -0,0 +1,9 @@
+{ pkgs ? import <nixpkgs> {}}:
+
+pkgs.mkShell {
+  packages = [
+    pkgs.go
+    pkgs.gopls
+    pkgs.gotools
+  ];
+}
diff --git a/default.nix~ b/default.nix~
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index 0000000..2ef9784
--- /dev/null
+++ b/default.nix~
@@ -0,0 +1,8 @@
+{ pkgs ? import <nixpkgs> {}}:
+
+pkgs.mkShell {
+  packages = [
+    pkgs.go
+    pkgs.gopls
+  ];
+}
diff --git a/dup/dup1.go b/dup/dup1.go
new file mode 100644
index 0000000..fc9e3f3
--- /dev/null
+++ b/dup/dup1.go
@@ -0,0 +1,26 @@
+// Dup1 prints the text of each line that appears more than
+// once in the standard input, preceeded by its count.
+
+package main
+
+import(
+	"bufio"
+	"fmt"
+	"os"
+)
+
+func main() {
+	counts := make(map[string]int)
+	input := bufio.NewScanner(os.Stdin)
+
+	for input.Scan() {
+		counts[input.Text()]++
+	}
+	//NOTE: ingnoring potential errors from input.Err()
+	for line, n := range counts {
+		if n > 1 {
+			fmt.Printf("%d\t%s\n", n , line)
+		}
+	}
+	
+}
diff --git a/dup/dup1.go~ b/dup/dup1.go~
new file mode 100644
index 0000000..e69de29
diff --git a/dup2/dup2.go b/dup2/dup2.go
new file mode 100644
index 0000000..6fdb424
--- /dev/null
+++ b/dup2/dup2.go
@@ -0,0 +1,33 @@
+package main
+
+import (
+	"bufio"
+	"fmt"
+	"os"
+)
+
+func main() {
+	counts := make(map[string]int)
+	files := os.Args[1:]
+	if len(files) == 0 {
+		countLines(os.Stdin, counts)
+	} else {
+		for _, arg := range files {
+			f, err := os.Open(arg)
+			if err != nil {
+				fmt.Fprintf(os.Stderr, "dup2: %v\n", err)
+				continue
+			}
+			countLines(f, counts)
+			f.Close()
+		}
+	}
+	
+}
+
+func countLines(f *os.File, counts map[string]int) {
+	input := bufio.NewScanner(f)
+	for input.Scan() {
+		counts[input.Text()]++
+	}
+}
diff --git a/dup2/dup2.go~ b/dup2/dup2.go~
new file mode 100644
index 0000000..e69de29
diff --git a/dup2/test.txt b/dup2/test.txt
new file mode 100644
index 0000000..d0c7fbe
--- /dev/null
+++ b/dup2/test.txt
@@ -0,0 +1,4 @@
+test
+test
+test
+test
diff --git a/dup3/hello b/dup3/hello
new file mode 100644
index 0000000..74619c5
--- /dev/null
+++ b/dup3/hello
@@ -0,0 +1,11 @@
+hello
+hello
+hello
+hello
+world
+world
+world
+world
+world
+hello
+hello
diff --git a/dup3/main.go b/dup3/main.go
new file mode 100644
index 0000000..08e8397
--- /dev/null
+++ b/dup3/main.go
@@ -0,0 +1,27 @@
+package main
+
+import (
+	"fmt"
+	"io/ioutil"
+	"os"
+	"strings"
+)
+
+func main() {
+	counts := make(map[string]int)
+	for _, filname := range os.Args[1:] {
+		data, err := ioutil.ReadFile(filname)
+		if err != nil {
+			fmt.Fprint(os.Stderr, "dup3: %v\n", err)
+			continue
+		}
+		for _, line := range strings.Split(string(data), "\n") {
+			counts[line]++
+		}
+	}
+	for line, n := range counts {
+		if n > 1 {
+			fmt.Printf("%d\t%s\n", n, line)
+		}
+	}
+}
diff --git a/dup3/main.go~ b/dup3/main.go~
new file mode 100644
index 0000000..e69de29
diff --git a/echov1/echo1 b/echov1/echo1
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diff --git a/echov1/echo1.go b/echov1/echo1.go
new file mode 100644
index 0000000..b686f00
--- /dev/null
+++ b/echov1/echo1.go
@@ -0,0 +1,16 @@
+//Echo1 prints its command-line arguments.
+package main
+
+import (
+	"fmt"
+	"os"
+)
+
+func main() {
+	var s, sep string
+	for i := 1;i < len(os.Args); i++ {
+		s += sep + os.Args[i]
+		sep = " "
+	}
+	fmt.Println(s)
+}
diff --git a/echov2/echo b/echov2/echo
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diff --git a/echov2/echo.go b/echov2/echo.go
new file mode 100644
index 0000000..1c94098
--- /dev/null
+++ b/echov2/echo.go
@@ -0,0 +1,19 @@
+// Echov2 prints its command-line arguments.
+package main
+
+import (
+	"fmt"
+	"os"
+)
+
+func main() {
+	s, sep := "", ""
+	for _, arg := range os.Args[1:] {
+		s += sep + arg
+		sep = " "
+	}
+	fmt.Println(s)
+	for i, v := range os.Args[1:] {
+		println(i,v)
+	}
+}
diff --git a/echov2/echo.go~ b/echov2/echo.go~
new file mode 100644
index 0000000..e69de29
diff --git a/echov3/echo b/echov3/echo
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diff --git a/echov3/echo.go b/echov3/echo.go
new file mode 100644
index 0000000..ec444f3
--- /dev/null
+++ b/echov3/echo.go
@@ -0,0 +1,13 @@
+package main
+
+import (
+	"fmt"
+	"os"
+	"strings"
+)
+
+func main() {
+	fmt.Println(strings.Join(os.Args[1:], " "))
+	fmt.Print(os.Args[0:])
+	
+}
diff --git a/echov3/echo.go~ b/echov3/echo.go~
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index 0000000..e69de29
diff --git a/fetch/fetch b/fetch/fetch
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diff --git a/fetch/main.go b/fetch/main.go
new file mode 100644
index 0000000..4136c33
--- /dev/null
+++ b/fetch/main.go
@@ -0,0 +1,25 @@
+package main
+
+import (
+	"fmt"
+	"io/ioutil"
+	"net/http"
+	"os"
+)
+
+func main() {
+	for _, url := range os.Args[1:] {
+		resp, err := http.Get(url)
+		if err != nil {
+			fmt.Fprintf(os.Stderr, "fetch: %v\n", err)
+			os.Exit(1)
+		}
+		b, err := ioutil.ReadAll(resp.Body)
+		resp.Body.Close()
+		if err != nil {
+			fmt.Fprintf(os.Stderr, "fetch: reading %s: %v\n", url, err)
+			os.Exit(1)
+		}
+		fmt.Printf("%s", b)
+	}
+}
diff --git a/fetch/main.go~ b/fetch/main.go~
new file mode 100644
index 0000000..e69de29
diff --git a/hello/helloworld.go b/hello/helloworld.go
new file mode 100644
index 0000000..69b53fa
--- /dev/null
+++ b/hello/helloworld.go
@@ -0,0 +1,7 @@
+package main
+
+import "fmt"
+
+func main() {
+	fmt.Println("hello 世界")
+}
diff --git a/helloworld.go~ b/helloworld.go~
new file mode 100644
index 0000000..c048119
--- /dev/null
+++ b/helloworld.go~
@@ -0,0 +1,7 @@
+package main
+
+import "fmt"
+
+func main() {
+	fmt.Println("hello world")
+}
diff --git a/lisajous/hello.gif b/lisajous/hello.gif
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diff --git a/lisajous/lisajous b/lisajous/lisajous
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diff --git a/lisajous/lisajous.go b/lisajous/lisajous.go
new file mode 100644
index 0000000..3f9ff9c
--- /dev/null
+++ b/lisajous/lisajous.go
@@ -0,0 +1,49 @@
+// Lisajous generates GIF animations of random Lisajous figures.
+package main
+
+import (
+	"image"
+	"image/color"
+	"image/gif"
+	"io"
+	"math"
+	"math/rand"
+	"os"
+)
+
+var palette = [] color.Color{color.White, color.Black}
+
+const (
+	whiteIndex = 0
+	blackindex = 1
+)
+
+func main() {
+	lisajous(os.Stdout)
+}
+
+func lisajous(out io.Writer) {
+	const (
+		cycles = 5
+		res = 0.001
+		size = 100
+		nframes = 64
+		delay = 8
+	)
+	freq := rand.Float64() * 3.0
+	anim := gif.GIF{LoopCount: nframes}
+	phase := 0.0
+	for i := 0; i < nframes; i++ {
+		rect := image.Rect(0, 0, 2*size+1, 2*size+1)
+		img := image.NewPaletted(rect, palette)
+		for t := 0.0; t < cycles*2*math.Pi; t += res {
+			x := math.Sin(t)
+			y := math.Sin(t*freq + phase)
+			img.SetColorIndex(size+int(x*size+0.5), size+int(y*size+0.5), blackindex)
+		}
+		phase += 0.1
+		anim.Delay = append(anim.Delay, delay)
+		anim.Image = append(anim.Image, img)
+	}
+	gif.EncodeAll(out, &anim)
+}
diff --git a/lisajous/lisajous.go~ b/lisajous/lisajous.go~
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diff --git a/lisajous/out.gif b/lisajous/out.gif
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