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mc/cat-main.go

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/*
* Minio Client, (C) 2015 Minio, Inc.
*
* 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 main
import (
"io"
"os"
"syscall"
"github.com/minio/cli"
"github.com/minio/minio/pkg/probe"
)
// Help message.
var catCmd = cli.Command{
Name: "cat",
Usage: "Display contents of a file",
Action: mainCat,
CustomHelpTemplate: `NAME:
mc {{.Name}} - {{.Usage}}
USAGE:
mc {{.Name}}{{if .Flags}} [ARGS...]{{end}} SOURCE [SOURCE...] {{if .Description}}
DESCRIPTION:
{{.Description}}{{end}}{{if .Flags}}
FLAGS:
{{range .Flags}}{{.}}
{{end}}{{ end }}
EXAMPLES:
1. Concantenate an object from Amazon S3 cloud storage to mplayer standard input.
$ mc {{.Name}} https://s3.amazonaws.com/ferenginar/klingon_opera_aktuh_maylotah.ogg | mplayer -
2. Concantenate a file from local filesystem to standard output.
$ mc {{.Name}} khitomer-accords.txt
3. Concantenate multiple files from local filesystem to standard output.
$ mc {{.Name}} *.txt > newfile.txt
4. Concatenate a non english file name from Amazon S3 cloud storage.
$ mc {{.Name}} s3:andoria/本語 > /tmp/本語
`,
}
func mainCat(ctx *cli.Context) {
stdinMode := false
if globalMimicFlag {
if !ctx.Args().Present() {
stdinMode = true
}
} else if !ctx.Args().Present() || ctx.Args().First() == "help" {
cli.ShowCommandHelpAndExit(ctx, "cat", 1) // last argument is exit code
}
if stdinMode {
fatalIf(catOut(os.Stdin).Trace(), "Unable to read from stdin.")
} else {
// Convert arguments to URLs: expand alias, fix format...
for _, arg := range ctx.Args() {
fatalIf(catURL(arg).Trace(arg), "Unable to read from "+arg+".")
}
}
}
func catURL(sourceURL string) *probe.Error {
config := mustGetMcConfig()
URL, err := getCanonicalizedURL(sourceURL, config.Aliases)
if err != nil {
return err.Trace(sourceURL)
}
sourceClnt, err := source2Client(URL)
if err != nil {
return err.Trace(URL)
}
// Ignore size, since os.Stat() would not return proper size all the time for local filesystem for example /proc files.
reader, _, err := sourceClnt.GetObject(0, 0)
if err != nil {
return err.Trace(URL)
}
defer reader.Close()
return catOut(reader).Trace(URL)
}
func catOut(r io.Reader) *probe.Error {
// read till EOF
if _, err := io.Copy(os.Stdout, r); err != nil {
switch e := err.(type) {
case *os.PathError:
if e.Err == syscall.EPIPE {
// stdout closed by the user. Gracefully exit.
return nil
}
return probe.NewError(err)
default:
return probe.NewError(err)
}
}
return nil
}