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support arbitrary values for `Location`

This commit is contained in:
Sridhar Ratnakumar 2013-07-12 15:30:31 -07:00
parent 6af3d03d43
commit 1e2bc8afe8
2 changed files with 5 additions and 8 deletions
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2
cmd/gotail/gotail.go
View File

@ -11,7 +11,7 @@ import (
func args2config() tail.Config { func args2config() tail.Config {
config := tail.Config{Follow: true} config := tail.Config{Follow: true}
flag.IntVar(&config.Location, "n", 0, "tail from the last Nth location") flag.Int64Var(&config.Location, "n", 0, "tail from the last Nth location")
flag.BoolVar(&config.Follow, "f", false, "wait for additional data to be appended to the file") flag.BoolVar(&config.Follow, "f", false, "wait for additional data to be appended to the file")
flag.BoolVar(&config.ReOpen, "F", false, "follow, and track file rename/rotation") flag.BoolVar(&config.ReOpen, "F", false, "follow, and track file rename/rotation")
flag.BoolVar(&config.Poll, "p", false, "use polling, instead of inotify") flag.BoolVar(&config.Poll, "p", false, "use polling, instead of inotify")

11
tail.go
View File

@ -26,7 +26,7 @@ type Line struct {
// Config is used to specify how a file must be tailed. // Config is used to specify how a file must be tailed.
type Config struct { type Config struct {
Location int // Tail from last N lines (tail -n) Location int64 // Tail from last N lines (tail -n)
Follow bool // Continue looking for new lines (tail -f) Follow bool // Continue looking for new lines (tail -f)
ReOpen bool // Reopen recreated files (tail -F) ReOpen bool // Reopen recreated files (tail -F)
MustExist bool // Fail early if the file does not exist MustExist bool // Fail early if the file does not exist
@ -55,10 +55,6 @@ type Tail struct {
// invoke the `Wait` or `Err` method after finishing reading from the // invoke the `Wait` or `Err` method after finishing reading from the
// `Lines` channel. // `Lines` channel.
func TailFile(filename string, config Config) (*Tail, error) { func TailFile(filename string, config Config) (*Tail, error) {
if !(config.Location == 0 || config.Location == -1) {
panic("only 0/-1 values are supported for Location.")
}
if config.ReOpen && !config.Follow { if config.ReOpen && !config.Follow {
panic("cannot set ReOpen without Follow.") panic("cannot set ReOpen without Follow.")
} }
@ -143,8 +139,9 @@ func (tail *Tail) tailFileSync() {
} }
// Seek to requested location on first open of the file. // Seek to requested location on first open of the file.
if tail.Location == 0 { if tail.Location >= 0 {
_, err := tail.file.Seek(0, 2) // Seek to the file end // Seek relative to file end
_, err := tail.file.Seek(tail.Location, 2)
if err != nil { if err != nil {
tail.Killf("Seek error on %s: %s", tail.Filename, err) tail.Killf("Seek error on %s: %s", tail.Filename, err)
return return