oshelper
Package oshelper contains helpers for Go’s os package.
go get github.com/solsw/oshelper
import "github.com/solsw/oshelper"
Constants
NewLine
const NewLine = "\r\n" // on Windows
const NewLine = "\n" // on other platforms
Platform-specific end-of-line marker, selected at build time.
Files and directories
FileExists, FileExistsFunc
func FileExists(filename string) (bool, error)
func FileExistsFunc(filename string, f func(string) string) (bool, error)
Report whether a regular file filename exists. An empty filename is an error.
If filename exists but is not a regular file, an error is returned; in
FileExistsFunc, f (if not nil) processes filename before it is embedded
in that error (e.g. f may extract just the file name from the full path).
DirExists, DirExistsFunc
func DirExists(dirname string) (bool, error)
func DirExistsFunc(dirname string, f func(string) string) (bool, error)
Report whether a directory dirname exists. An empty dirname is an error.
If dirname exists but is not a directory, an error is returned; in
DirExistsFunc, f (if not nil) processes dirname before it is embedded
in that error (e.g. f may shorten an excessively long dirname).
ClearDir
func ClearDir(dirname string) error
Removes the contents of the directory dirname, leaving the directory itself in place.
RandomOverFile
func RandomOverFile(filename string) error
Overwrites the contents of the file filename with cryptographically random
data of the same size, then syncs the file to stable storage.
WipeFile
func WipeFile(filename string) error
First overwrites the contents of the file filename with random data
(see RandomOverFile), then removes the file.
TempFileBase
func TempFileBase(pattern string) (string, error)
Returns just the name (without directory) of a temporary file. The file itself
is created and immediately removed. See os.CreateTemp
for pattern usage.
ExeDir
func ExeDir() (string, error)
Returns an absolute representation of the directory name of the executable that started the current process.
Environment variables
GetenvDef
func GetenvDef(key, def string) string
Retrieves the value of the environment variable named by key.
If the variable is not present or has an empty value, def is returned.
GetenvErr
func GetenvErr(key string) (string, error)
Retrieves the value of the environment variable named by key.
If the variable is not present or has an empty value, an error is returned.
Reading and writing
Freadln, Readln
func Freadln(r io.Reader) (string, error)
func Readln() (string, error)
Freadln reads from r until the first end-of-line marker (see
bufio.ScanLines) and returns the line
stripped of any trailing end-of-line marker. Returns io.EOF if r is at EOF
before any data is read. Readln is like Freadln, but reads from standard input.
ReadFileStrings
func ReadFileStrings(filename string) ([]string, error)
Returns the contents of the file filename as a []string, one element per line.
WriteFileStrings, WriteFileStringsNewLine
func WriteFileStrings(filename string, ss []string, perm os.FileMode) error
func WriteFileStringsNewLine(filename string, ss []string, perm os.FileMode, newLine string) error
Write ss to the named file. Each string (including the last one) is followed
by newLine (WriteFileStringsNewLine) or by NewLine (WriteFileStrings).
If ss is empty, only the newline is written. See
os.WriteFile for perm usage.
SyncFileWriter
type SyncFileWriter struct { /* unexported fields */ }
func NewSyncFileWriter(f *os.File) *SyncFileWriter
func (sfw *SyncFileWriter) File() *os.File
func (sfw *SyncFileWriter) Write(p []byte) (n int, err error)
An os.File-based
io.Writer implementation that calls
os.File.Sync after each write, so every
write is committed to stable storage. File returns the underlying file.
Standard input
StdinRedirected, ErrStdinNotRedirected
var ErrStdinNotRedirected = errors.New("standard input is not redirected (file '<' or pipe '|')")
func StdinRedirected() error
StdinRedirected returns nil if standard input is redirected (from a file via
< or a pipe via |). Otherwise, it returns ErrStdinNotRedirected.