github.com/spinnaker/spin@v1.30.0/util/args_reader.go (about) 1 // Copyright (c) 2019, Google, Inc. 2 // 3 // Licensed under the Apache License, Version 2.0 (the "License"); 4 // you may not use this file except in compliance with the License. 5 // You may obtain a copy of the License at 6 // 7 // http://www.apache.org/licenses/LICENSE-2.0 8 // 9 // Unless required by applicable law or agreed to in writing, software 10 // distributed under the License is distributed on an "AS IS" BASIS, 11 // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 12 // See the License for the specific language governing permissions and 13 // limitations under the License. 14 15 package util 16 17 import ( 18 "bufio" 19 "errors" 20 "os" 21 ) 22 23 func ReadArgsOrStdin(args []string) (string, error) { 24 if len(args) > 0 { 25 return args[0], nil 26 } 27 28 stdin := os.Stdin 29 fi, err := stdin.Stat() 30 if err != nil { 31 return "", err 32 } 33 34 pipedStdin := (fi.Mode() & os.ModeCharDevice) == 0 35 if fi.Size() <= 0 && !pipedStdin { 36 return "", errors.New("no args or STDIN provided") 37 } 38 39 scanner := bufio.NewScanner(os.Stdin) 40 input := "" 41 for scanner.Scan() { 42 input = scanner.Text() 43 } 44 return input, nil 45 }