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tail.go
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tail.go
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/*
Copyright (c) 2016 VMware, Inc. All Rights Reserved.
Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at
http://www.apache.org/licenses/LICENSE-2.0
Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
*/
package datastore
import (
"context"
"flag"
"io"
"os"
"time"
"github.com/vmware/govmomi/govc/cli"
"github.com/vmware/govmomi/govc/flags"
)
type tail struct {
*flags.DatastoreFlag
*flags.HostSystemFlag
count int64
lines int
follow bool
}
func init() {
cli.Register("datastore.tail", &tail{})
}
func (cmd *tail) Register(ctx context.Context, f *flag.FlagSet) {
cmd.DatastoreFlag, ctx = flags.NewDatastoreFlag(ctx)
cmd.DatastoreFlag.Register(ctx, f)
cmd.HostSystemFlag, ctx = flags.NewHostSystemFlag(ctx)
cmd.HostSystemFlag.Register(ctx, f)
f.Int64Var(&cmd.count, "c", -1, "Output the last NUM bytes")
f.IntVar(&cmd.lines, "n", 10, "Output the last NUM lines")
f.BoolVar(&cmd.follow, "f", false, "Output appended data as the file grows")
}
func (cmd *tail) Description() string {
return `Output the last part of datastore files.
Examples:
govc datastore.tail -n 100 vm-name/vmware.log
govc datastore.tail -n 0 -f vm-name/vmware.log`
}
func (cmd *tail) Process(ctx context.Context) error {
if err := cmd.DatastoreFlag.Process(ctx); err != nil {
return err
}
if err := cmd.HostSystemFlag.Process(ctx); err != nil {
return err
}
return nil
}
func (cmd *tail) Usage() string {
return "PATH"
}
func (cmd *tail) Run(ctx context.Context, f *flag.FlagSet) error {
if f.NArg() != 1 {
return flag.ErrHelp
}
p := cmd.Args(f.Args())[0]
ds, err := cmd.Datastore()
if err != nil {
return err
}
h, err := cmd.HostSystemIfSpecified()
if err != nil {
return err
}
if h != nil {
ctx = ds.HostContext(ctx, h)
}
file, err := ds.Open(ctx, p.Path)
if err != nil {
return err
}
var reader io.ReadCloser = file
var offset int64
if cmd.count >= 0 {
info, serr := file.Stat()
if serr != nil {
return serr
}
if info.Size() > cmd.count {
offset = info.Size() - cmd.count
_, err = file.Seek(offset, io.SeekStart)
if err != nil {
return err
}
}
} else if cmd.lines >= 0 {
err = file.Tail(cmd.lines)
if err != nil {
return err
}
}
if cmd.follow {
reader = file.Follow(time.Second)
}
_, err = io.Copy(os.Stdout, reader)
_ = reader.Close()
return err
}