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Simple Shell With Custom
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package main | |
import ( | |
"bufio" | |
"errors" | |
"fmt" | |
"os" | |
"os/exec" | |
"strconv" | |
"strings" | |
) | |
func main() { | |
reader := bufio.NewReader(os.Stdin) | |
for { | |
fmt.Print("$ ") | |
cmdString, err := reader.ReadString('\n') | |
if err != nil { | |
fmt.Fprintln(os.Stderr, err) | |
} | |
err = runCommand(cmdString) | |
if err != nil { | |
fmt.Fprintln(os.Stderr, err) | |
} | |
} | |
} | |
func runCommand(commandStr string) error { | |
commandStr = strings.TrimSuffix(commandStr, "\n") | |
arrCommandStr := strings.Fields(commandStr) | |
switch arrCommandStr[0] { | |
case "exit": | |
os.Exit(0) | |
case "plus": | |
// not using `sum` because it's a default command in unix. | |
if len(arrCommandStr) < 3 { | |
return errors.New("Required for 2 arguments") | |
} | |
arrNum := []int64{} | |
for i, arg := range arrCommandStr { | |
if i == 0 { | |
continue | |
} | |
n, _ := strconv.ParseInt(arg, 10, 64) | |
arrNum = append(arrNum, n) | |
} | |
fmt.Fprintln(os.Stdout, sum(arrNum...)) | |
return nil | |
// add another case here for custom commands. | |
} | |
cmd := exec.Command(arrCommandStr[0], arrCommandStr[1:]...) | |
cmd.Stderr = os.Stderr | |
cmd.Stdout = os.Stdout | |
return cmd.Run() | |
} | |
func sum(numbers ...int64) int64 { | |
res := int64(0) | |
for _, num := range numbers { | |
res += num | |
} | |
return res | |
} |
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