jnml@fsc-r630:~/src/tmp/SO/13789882$ ls
foo.txt  main.go
jnml@fsc-r630:~/src/tmp/SO/13789882$ cat main.go 
package main

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

func main() {
        src, err := ioutil.ReadFile("foo.txt")
        if err != nil {
                log.Fatal(err)
        }

        src = bytes.Replace(src, []byte("BEGIN"), []byte("{"), -1)
        src = bytes.Replace(src, []byte("END"), []byte("}"), -1)
        if err = ioutil.WriteFile("beer2.txt", src, 0666); err != nil {
                log.Fatal(err)
        }
}
jnml@fsc-r630:~/src/tmp/SO/13789882$ cat foo.txt 
BEGIN
  FILE F(KIND=REMOTE);
  EBCDIC ARRAY E[0:11];
  REPLACE E BY "HELLO WORLD!";
  WRITE(F, *, E);
END.
jnml@fsc-r630:~/src/tmp/SO/13789882$ go run main.go 
jnml@fsc-r630:~/src/tmp/SO/13789882$ cat beer2.txt 
{
  FILE F(KIND=REMOTE);
  EBCDIC ARRAY E[0:11];
  REPLACE E BY "HELLO WORLD!";
  WRITE(F, *, E);
}.
jnml@fsc-r630:~/src/tmp/SO/13789882$