Documentation

Overview

    Package ioutil implements some I/O utility functions.

    As of Go 1.16, the same functionality is now provided by package io or package os, and those implementations should be preferred in new code. See the specific function documentation for details.

    Index

    Examples

    Constants

    This section is empty.

    Variables

    View Source
    var Discard io.Writer = io.Discard

      Discard is an io.Writer on which all Write calls succeed without doing anything.

      As of Go 1.16, this value is simply io.Discard.

      Functions

      func NopCloser

      func NopCloser(r io.Reader) io.ReadCloser

        NopCloser returns a ReadCloser with a no-op Close method wrapping the provided Reader r.

        As of Go 1.16, this function simply calls io.NopCloser.

        func ReadAll

        func ReadAll(r io.Reader) ([]byte, error)

          ReadAll reads from r until an error or EOF and returns the data it read. A successful call returns err == nil, not err == EOF. Because ReadAll is defined to read from src until EOF, it does not treat an EOF from Read as an error to be reported.

          As of Go 1.16, this function simply calls io.ReadAll.

          Example
          Output:
          
          Go is a general-purpose language designed with systems programming in mind.
          

          func ReadDir

          func ReadDir(dirname string) ([]fs.FileInfo, error)

            ReadDir reads the directory named by dirname and returns a list of fs.FileInfo for the directory's contents, sorted by filename. If an error occurs reading the directory, ReadDir returns no directory entries along with the error.

            As of Go 1.16, os.ReadDir is a more efficient and correct choice: it returns a list of fs.DirEntry instead of fs.FileInfo, and it returns partial results in the case of an error midway through reading a directory.

            Example
            Output:
            
            

            func ReadFile

            func ReadFile(filename string) ([]byte, error)

              ReadFile reads the file named by filename and returns the contents. A successful call returns err == nil, not err == EOF. Because ReadFile reads the whole file, it does not treat an EOF from Read as an error to be reported.

              As of Go 1.16, this function simply calls os.ReadFile.

              Example
              Output:
              
              File contents: Hello, Gophers!
              

              func TempDir

              func TempDir(dir, pattern string) (name string, err error)

                TempDir creates a new temporary directory in the directory dir. The directory name is generated by taking pattern and applying a random string to the end. If pattern includes a "*", the random string replaces the last "*". TempDir returns the name of the new directory. If dir is the empty string, TempDir uses the default directory for temporary files (see os.TempDir). Multiple programs calling TempDir simultaneously will not choose the same directory. It is the caller's responsibility to remove the directory when no longer needed.

                Example
                Output:
                
                
                Example (Suffix)
                Output:
                
                

                func TempFile

                func TempFile(dir, pattern string) (f *os.File, err error)

                  TempFile creates a new temporary file in the directory dir, opens the file for reading and writing, and returns the resulting *os.File. The filename is generated by taking pattern and adding a random string to the end. If pattern includes a "*", the random string replaces the last "*". If dir is the empty string, TempFile uses the default directory for temporary files (see os.TempDir). Multiple programs calling TempFile simultaneously will not choose the same file. The caller can use f.Name() to find the pathname of the file. It is the caller's responsibility to remove the file when no longer needed.

                  Example
                  Output:
                  
                  
                  Example (Suffix)
                  Output:
                  
                  

                  func WriteFile

                  func WriteFile(filename string, data []byte, perm fs.FileMode) error

                    WriteFile writes data to a file named by filename. If the file does not exist, WriteFile creates it with permissions perm (before umask); otherwise WriteFile truncates it before writing, without changing permissions.

                    As of Go 1.16, this function simply calls os.WriteFile.

                    Example
                    Output:
                    
                    

                    Types

                    This section is empty.