Jump to specific line in file in Go

In Go is it possible to jump to particular line number in a file and delete it? Something like linecache in python.

I'm trying to match some substrings in a file and remove the corresponding lines. The matching part I've taken care of and I have an array with line numbers I need to delete but I'm stuck on how to delete the matching lines in the file.

This is an old question, but if anyone is looking for a solution I wrote a package that handles going to any line in a file. Link here. It can open a file and seek to any line position without reading the whole file into memory and splitting.

import "github.com/stoicperlman/fls"

// This is just a wrapper around os.OpenFile. Alternatively 
// you could open from os.File and use fls.LineFile(file) to get f
f, err := fls.OpenFile("test.log", os.O_CREATE|os.O_WRONLY, 0600)
defer f.Close()

// return begining line 1/begining of file
// equivalent to f.Seek(0, io.SeekStart)
pos, err := f.SeekLine(0, io.SeekStart)

// return begining line 2
pos, err := f.SeekLine(1, io.SeekStart)

// return begining of last line
pos, err := f.SeekLine(0, io.SeekEnd) 

// return begining of second to last line
pos, err := f.SeekLine(-1, io.SeekEnd) 

Unfortunately I'm not sure how you would delete, this just handles getting you to the correct position in the file. For your case you could use it to go to the line you want to delete and save the position. Then seek to the next line and save that as well. You now have the bookends of the line to delete.

// might want lineToDelete - 1
// this acts like 0 based array
pos1, err := f.SeekLine(lineToDelete, io.SeekStart)

// skip ahead 1 line
pos2, err := f.SeekLine(1, io.SeekCurrent)

// pos2 will be the position of the first character in next line
// might want pos2 - 1 depending on how the function works
DeleteBytesFromFileFunction(f, pos1, pos2)

Based on my read of the linecache module it takes a file and explodes it into an array based on '\n' line endings. You could replicate the same behavior in Go by using strings or bytes. You could also use the bufio library to read a file a line by line and only store or save the lines you want.

package main

import (
	"bytes"
	"fmt"
)
import "io/ioutil"

func main() {

	b, e := ioutil.ReadFile("filename.txt")
	if e != nil {
		panic(e)
	}
	array := bytes.Split(b, []byte("\n"))

	fmt.Printf("%v", array)
}

I wrote a small function that allowing you remove from a file a specific line.

package main

import (
    "io/ioutil"
    "os"
    "strings"
)

func main() {
    path := "path/to/file.txt"
    removeLine(path, 2)
}

func removeLine(path string, lineNumber int) {
    file, err := ioutil.ReadFile(path)
    if err != nil {
        panic(err)
    }

    info, _ := os.Stat(path)
    mode := info.Mode()

    array := strings.Split(string(file), "\n")
    array = append(array[:lineNumber], array[lineNumber+1:]...)
    ioutil.WriteFile(path, []byte(strings.Join(array, "\n")), mode)
}