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52 lines
815 B
52 lines
815 B
package main
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import (
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"bufio"
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"fmt"
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"io"
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"log"
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"os"
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"regexp"
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)
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const USAGE = `Usage: greppish <regex> [filename]
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Prints lines matching <regex> in [filename] or standard input.`
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func main() {
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if len(os.Args) < 2 {
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fmt.Println(USAGE)
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os.Exit(1)
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}
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regMatch, err := regexp.Compile(os.Args[1])
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if err != nil {
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log.Fatal("Problem compiling regex: ", err)
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}
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inbuf := bufio.NewReader(os.Stdin)
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if len(os.Args) > 2 {
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infile, err := os.Open(os.Args[2])
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if err != nil {
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log.Fatal("Problem opening input file: ", err)
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}
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inbuf = bufio.NewReader(infile)
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}
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var line string
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for {
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line, err = inbuf.ReadString('\n')
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if err != nil {
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if err == io.EOF {
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os.Exit(0)
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}
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log.Fatal("Problem reading input: ", err)
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}
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if regMatch.MatchString(line) {
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fmt.Printf(line)
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}
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}
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}
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