os

package
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 Go to latest Published: Jun 9, 2011 License: BSD-3-Clause Imports: 3 Imported by: 0

Documentation

Overview

Package os provides a platform-independent interface to operating system functionality. The design is Unix-like.

The os package provides a platform-independent interface to operating system functionality. The design is Unix-like.

Index

Constants

View Source 
const (
	WNOHANG   = syscall.WNOHANG   // Don't wait if no process has exited.
	WSTOPPED  = syscall.WSTOPPED  // If set, status of stopped subprocesses is also reported.
	WUNTRACED = syscall.WUNTRACED // Usually an alias for WSTOPPED.
	WRUSAGE   = 1 << 20           // Record resource usage.
)

Options for Wait.

View Source 
const (
	O_RDONLY   int = syscall.O_RDONLY   // open the file read-only.
	O_WRONLY   int = syscall.O_WRONLY   // open the file write-only.
	O_RDWR     int = syscall.O_RDWR     // open the file read-write.
	O_APPEND   int = syscall.O_APPEND   // append data to the file when writing.
	O_ASYNC    int = syscall.O_ASYNC    // generate a signal when I/O is available.
	O_CREATE   int = syscall.O_CREAT    // create a new file if none exists.
	O_EXCL     int = syscall.O_EXCL     // used with O_CREATE, file must not exist
	O_NOCTTY   int = syscall.O_NOCTTY   // do not make file the controlling tty.
	O_NONBLOCK int = syscall.O_NONBLOCK // open in non-blocking mode.
	O_NDELAY   int = O_NONBLOCK         // synonym for O_NONBLOCK
	O_SYNC     int = syscall.O_SYNC     // open for synchronous I/O.
	O_TRUNC    int = syscall.O_TRUNC    // if possible, truncate file when opened.
)

Flags to Open wrapping those of the underlying system. Not all flags may be implemented on a given system.

View Source 
const (
	SEEK_SET int = 0 // seek relative to the origin of the file
	SEEK_CUR int = 1 // seek relative to the current offset
	SEEK_END int = 2 // seek relative to the end
)

Seek whence values.

View Source 
const (
	PathSeparator     = '/' // OS-specific path separator
	PathListSeparator = ':' // OS-specific path list separator
)
View Source 
const DevNull = "/dev/null"

DevNull is the name of the operating system's “null device.” On Unix-like systems, it is "/dev/null"; on Windows, "NUL".

Variables

View Source 
var (
	Stdin  = NewFile(syscall.Stdin, "/dev/stdin")
	Stdout = NewFile(syscall.Stdout, "/dev/stdout")
	Stderr = NewFile(syscall.Stderr, "/dev/stderr")
)

Stdin, Stdout, and Stderr are open Files pointing to the standard input, standard output, and standard error file descriptors.

View Source 
var Args []string // provided by runtime
View Source 
var ENOENV = NewError("no such environment variable")

ENOENV is the Error indicating that an environment variable does not exist.

View Source 
var Envs []string // provided by runtime

Functions

func Clearenv 

func Clearenv()

Clearenv deletes all environment variables.

func Create 

func Create(name string) (file *File, err Error)

Create creates the named file mode 0666 (before umask), truncating it if it already exists. If successful, methods on the returned File can be used for I/O; the associated file descriptor has mode O_RDWR. It returns the File and an Error, if any.

func Environ 

func Environ() []string

Environ returns an array of strings representing the environment, in the form "key=value".

func Exit 

func Exit(code int)

Exit causes the current program to exit with the given status code. Conventionally, code zero indicates success, non-zero an error.

func Expand 

func Expand(s string, mapping func(string) string) string

Expand replaces ${var} or $var in the string based on the mapping function. Invocations of undefined variables are replaced with the empty string.

func FindProcess 

func FindProcess(pid int) (p *Process, err Error)

FindProcess looks for a running process by its pid. The Process it returns can be used to obtain information about the underlying operating system process.

func Getegid 

func Getegid() int

Getegid returns the numeric effective group id of the caller.

func Getenv 

func Getenv(key string) string

Getenv retrieves the value of the environment variable named by the key. It returns the value, which will be empty if the variable is not present.

func Geteuid 

func Geteuid() int

Geteuid returns the numeric effective user id of the caller.

func Getgid 

func Getgid() int

Getgid returns the numeric group id of the caller.

func Getpagesize 

func Getpagesize() int

Getpagesize returns the underlying system's memory page size.

func Getpid 

func Getpid() int

Getpid returns the process id of the caller.

func Getppid 

func Getppid() int

Getppid returns the process id of the caller's parent.

func Getuid 

func Getuid() int

Getuid returns the numeric user id of the caller.

func IsPathSeparator 

func IsPathSeparator(c uint8) bool

IsPathSeparator returns true if c is a directory separator character.

func Lstat 

func Lstat(name string) (fi *FileInfo, err Error)

Lstat returns the FileInfo structure describing the named file and an error, if any. If the file is a symbolic link, the returned FileInfo describes the symbolic link. Lstat makes no attempt to follow the link.

func Open 

func Open(name string) (file *File, err Error)

Open opens the named file for reading. If successful, methods on the returned file can be used for reading; the associated file descriptor has mode O_RDONLY. It returns the File and an Error, if any.

func OpenFile 

func OpenFile(name string, flag int, perm uint32) (file *File, err Error)

OpenFile is the generalized open call; most users will use Open or Create instead. It opens the named file with specified flag (O_RDONLY etc.) and perm, (0666 etc.) if applicable. If successful, methods on the returned File can be used for I/O. It returns the File and an Error, if any.

func Pipe 

func Pipe() (r *File, w *File, err Error)

Pipe returns a connected pair of Files; reads from r return bytes written to w. It returns the files and an Error, if any.

func ShellExpand 

func ShellExpand(s string) string

ShellExpand replaces ${var} or $var in the string according to the values of the operating system's environment variables. References to undefined variables are replaced by the empty string.

func StartProcess 

func StartProcess(name string, argv []string, attr *ProcAttr) (p *Process, err Error)

StartProcess starts a new process with the program, arguments and attributes specified by name, argv and attr.

func Stat 

func Stat(name string) (fi *FileInfo, err Error)

Stat returns a FileInfo structure describing the named file and an error, if any. If name names a valid symbolic link, the returned FileInfo describes the file pointed at by the link and has fi.FollowedSymlink set to true. If name names an invalid symbolic link, the returned FileInfo describes the link itself and has fi.FollowedSymlink set to false.

func TempDir 

func TempDir() string

TempDir returns the default directory to use for temporary files.

func Wait 

func Wait(pid int, options int) (w *Waitmsg, err Error)

Wait waits for process pid to exit or stop, and then returns a Waitmsg describing its status and an Error, if any. The options (WNOHANG etc.) affect the behavior of the Wait call. Wait is equivalent to calling FindProcess and then Wait and Release on the result.

Types

type Errno 

type Errno int64

Errno is the Unix error number. Names such as EINVAL are simple wrappers to convert the error number into an Error.

func (Errno) String 

func (e Errno) String() string

func (Errno) Temporary 

func (e Errno) Temporary() bool

func (Errno) Timeout 

func (e Errno) Timeout() bool

type Error 

type Error interface {
	String() string
}

An Error can represent any printable error condition. 

var (
	EPERM        Error = Errno(syscall.EPERM)
	ENOENT       Error = Errno(syscall.ENOENT)
	ESRCH        Error = Errno(syscall.ESRCH)
	EINTR        Error = Errno(syscall.EINTR)
	EIO          Error = Errno(syscall.EIO)
	ENXIO        Error = Errno(syscall.ENXIO)
	E2BIG        Error = Errno(syscall.E2BIG)
	ENOEXEC      Error = Errno(syscall.ENOEXEC)
	EBADF        Error = Errno(syscall.EBADF)
	ECHILD       Error = Errno(syscall.ECHILD)
	EDEADLK      Error = Errno(syscall.EDEADLK)
	ENOMEM       Error = Errno(syscall.ENOMEM)
	EACCES       Error = Errno(syscall.EACCES)
	EFAULT       Error = Errno(syscall.EFAULT)
	EBUSY        Error = Errno(syscall.EBUSY)
	EEXIST       Error = Errno(syscall.EEXIST)
	EXDEV        Error = Errno(syscall.EXDEV)
	ENODEV       Error = Errno(syscall.ENODEV)
	ENOTDIR      Error = Errno(syscall.ENOTDIR)
	EISDIR       Error = Errno(syscall.EISDIR)
	EINVAL       Error = Errno(syscall.EINVAL)
	ENFILE       Error = Errno(syscall.ENFILE)
	EMFILE       Error = Errno(syscall.EMFILE)
	ENOTTY       Error = Errno(syscall.ENOTTY)
	EFBIG        Error = Errno(syscall.EFBIG)
	ENOSPC       Error = Errno(syscall.ENOSPC)
	ESPIPE       Error = Errno(syscall.ESPIPE)
	EROFS        Error = Errno(syscall.EROFS)
	EMLINK       Error = Errno(syscall.EMLINK)
	EPIPE        Error = Errno(syscall.EPIPE)
	EAGAIN       Error = Errno(syscall.EAGAIN)
	EDOM         Error = Errno(syscall.EDOM)
	ERANGE       Error = Errno(syscall.ERANGE)
	EADDRINUSE   Error = Errno(syscall.EADDRINUSE)
	ECONNREFUSED Error = Errno(syscall.ECONNREFUSED)
	ENAMETOOLONG Error = Errno(syscall.ENAMETOOLONG)
	EAFNOSUPPORT Error = Errno(syscall.EAFNOSUPPORT)
	ETIMEDOUT    Error = Errno(syscall.ETIMEDOUT)
	ENOTCONN     Error = Errno(syscall.ENOTCONN)
)

Commonly known Unix errors. 

var EOF Error = eofError(0)

EOF is the Error returned by Read when no more input is available. Functions should return EOF only to signal a graceful end of input. If the EOF occurs unexpectedly in a structured data stream, the appropriate error is either io.ErrUnexpectedEOF or some other error giving more detail.

func Chdir 

func Chdir(dir string) Error

Chdir changes the current working directory to the named directory.

func Chmod 

func Chmod(name string, mode uint32) Error

Chmod changes the mode of the named file to mode. If the file is a symbolic link, it changes the mode of the link's target.

func Chown 

func Chown(name string, uid, gid int) Error

Chown changes the numeric uid and gid of the named file. If the file is a symbolic link, it changes the uid and gid of the link's target.

func Chtimes 

func Chtimes(name string, atime_ns int64, mtime_ns int64) Error

Chtimes changes the access and modification times of the named file, similar to the Unix utime() or utimes() functions.

The argument times are in nanoseconds, although the underlying filesystem may truncate or round the values to a more coarse time unit.

func Exec 

func Exec(name string, argv []string, envv []string) Error

Exec replaces the current process with an execution of the named binary, with arguments argv and environment envv. If successful, Exec never returns. If it fails, it returns an Error. StartProcess is almost always a better way to execute a program.

func Getenverror 

func Getenverror(key string) (value string, err Error)

Getenverror retrieves the value of the environment variable named by the key. It returns the value and an error, if any.

func Getgroups 

func Getgroups() ([]int, Error)

Getgroups returns a list of the numeric ids of groups that the caller belongs to.

func Getwd 

func Getwd() (string, Error)

Getwd returns a rooted path name corresponding to the current directory. If the current directory can be reached via multiple paths (due to symbolic links), Getwd may return any one of them.

func Hostname 

func Hostname() (name string, err Error)

Hostname returns the host name reported by the kernel.

func Lchown 

func Lchown(name string, uid, gid int) Error

Lchown changes the numeric uid and gid of the named file. If the file is a symbolic link, it changes the uid and gid of the link itself. 

func Link(oldname, newname string) Error

Link creates a hard link.

func Mkdir 

func Mkdir(name string, perm uint32) Error

Mkdir creates a new directory with the specified name and permission bits. It returns an error, if any.

func MkdirAll 

func MkdirAll(path string, perm uint32) Error

MkdirAll creates a directory named path, along with any necessary parents, and returns nil, or else returns an error. The permission bits perm are used for all directories that MkdirAll creates. If path is already a directory, MkdirAll does nothing and returns nil.

func NewError 

func NewError(s string) Error

NewError converts s to an ErrorString, which satisfies the Error interface.

func NewSyscallError 

func NewSyscallError(syscall string, errno int) Error

NewSyscallError returns, as an Error, a new SyscallError with the given system call name and error details. As a convenience, if errno is 0, NewSyscallError returns nil. 

func Readlink(name string) (string, Error)

Readlink reads the contents of a symbolic link: the destination of the link. It returns the contents and an Error, if any.

func Remove 

func Remove(name string) Error

Remove removes the named file or directory.

func RemoveAll 

func RemoveAll(path string) Error

RemoveAll removes path and any children it contains. It removes everything it can but returns the first error it encounters. If the path does not exist, RemoveAll returns nil (no error).

func Rename 

func Rename(oldname, newname string) Error

Rename renames a file.

func Setenv 

func Setenv(key, value string) Error

Setenv sets the value of the environment variable named by the key. It returns an Error, if any. 

func Symlink(oldname, newname string) Error

Symlink creates a symbolic link.

func Time 

func Time() (sec int64, nsec int64, err Error)

Time returns the current time, in whole seconds and fractional nanoseconds, plus an Error if any. The current time is thus 1e9*sec+nsec, in nanoseconds. The zero of time is the Unix epoch.

func Truncate 

func Truncate(name string, size int64) Error

Truncate changes the size of the named file. If the file is a symbolic link, it changes the size of the link's target.

type ErrorString 

type ErrorString string

A helper type that can be embedded or wrapped to simplify satisfying Error.

func (ErrorString) String 

func (e ErrorString) String() string

func (ErrorString) Temporary 

func (e ErrorString) Temporary() bool

func (ErrorString) Timeout 

func (e ErrorString) Timeout() bool

type File 

type File struct {
	// contains filtered or unexported fields
}

File represents an open file descriptor.

func NewFile 

func NewFile(fd int, name string) *File

NewFile returns a new File with the given file descriptor and name.

func (*File) Chdir 

func (f *File) Chdir() Error

Chdir changes the current working directory to the file, which must be a directory.

func (*File) Chmod 

func (f *File) Chmod(mode uint32) Error

Chmod changes the mode of the file to mode.

func (*File) Chown 

func (f *File) Chown(uid, gid int) Error

Chown changes the numeric uid and gid of the named file.

func (*File) Close 

func (file *File) Close() Error

Close closes the File, rendering it unusable for I/O. It returns an Error, if any.

func (*File) Fd 

func (file *File) Fd() int

Fd returns the integer Unix file descriptor referencing the open file.

func (*File) Name 

func (file *File) Name() string

Name returns the name of the file as presented to Open.

func (*File) Read 

func (file *File) Read(b []byte) (n int, err Error)

Read reads up to len(b) bytes from the File. It returns the number of bytes read and an Error, if any. EOF is signaled by a zero count with err set to EOF.

func (*File) ReadAt 

func (file *File) ReadAt(b []byte, off int64) (n int, err Error)

ReadAt reads len(b) bytes from the File starting at byte offset off. It returns the number of bytes read and the Error, if any. EOF is signaled by a zero count with err set to EOF. ReadAt always returns a non-nil Error when n != len(b).

func (*File) Readdir 

func (file *File) Readdir(n int) (fi []FileInfo, err Error)

Readdir reads the contents of the directory associated with file and returns an array of up to n FileInfo structures, as would be returned by Lstat, in directory order. Subsequent calls on the same file will yield further FileInfos.

If n > 0, Readdir returns at most n FileInfo structures. In this case, if Readdir returns an empty slice, it will return a non-nil error explaining why. At the end of a directory, the error is os.EOF.

If n <= 0, Readdir returns all the FileInfo from the directory in a single slice. In this case, if Readdir succeeds (reads all the way to the end of the directory), it returns the slice and a nil os.Error. If it encounters an error before the end of the directory, Readdir returns the FileInfo read until that point and a non-nil error.

func (*File) Readdirnames 

func (f *File) Readdirnames(n int) (names []string, err Error)

Readdirnames reads and returns a slice of names from the directory f.

If n > 0, Readdirnames returns at most n names. In this case, if Readdirnames returns an empty slice, it will return a non-nil error explaining why. At the end of a directory, the error is os.EOF.

If n <= 0, Readdirnames returns all the names from the directory in a single slice. In this case, if Readdirnames succeeds (reads all the way to the end of the directory), it returns the slice and a nil os.Error. If it encounters an error before the end of the directory, Readdirnames returns the names read until that point and a non-nil error.

func (*File) Seek 

func (file *File) Seek(offset int64, whence int) (ret int64, err Error)

Seek sets the offset for the next Read or Write on file to offset, interpreted according to whence: 0 means relative to the origin of the file, 1 means relative to the current offset, and 2 means relative to the end. It returns the new offset and an Error, if any.

func (*File) Stat 

func (file *File) Stat() (fi *FileInfo, err Error)

Stat returns the FileInfo structure describing file. It returns the FileInfo and an error, if any.

func (*File) Sync 

func (file *File) Sync() (err Error)

Sync commits the current contents of the file to stable storage. Typically, this means flushing the file system's in-memory copy of recently written data to disk.

func (*File) Truncate 

func (f *File) Truncate(size int64) Error

Truncate changes the size of the file. It does not change the I/O offset.

func (*File) Write 

func (file *File) Write(b []byte) (n int, err Error)

Write writes len(b) bytes to the File. It returns the number of bytes written and an Error, if any. Write returns a non-nil Error when n != len(b).

func (*File) WriteAt 

func (file *File) WriteAt(b []byte, off int64) (n int, err Error)

WriteAt writes len(b) bytes to the File starting at byte offset off. It returns the number of bytes written and an Error, if any. WriteAt returns a non-nil Error when n != len(b).

func (*File) WriteString 

func (file *File) WriteString(s string) (ret int, err Error)

WriteString is like Write, but writes the contents of string s rather than an array of bytes.

type FileInfo 

type FileInfo struct {
	Dev             uint64 // device number of file system holding file.
	Ino             uint64 // inode number.
	Nlink           uint64 // number of hard links.
	Mode            uint32 // permission and mode bits.
	Uid             int    // user id of owner.
	Gid             int    // group id of owner.
	Rdev            uint64 // device type for special file.
	Size            int64  // length in bytes.
	Blksize         int64  // size of blocks, in bytes.
	Blocks          int64  // number of blocks allocated for file.
	Atime_ns        int64  // access time; nanoseconds since epoch.
	Mtime_ns        int64  // modified time; nanoseconds since epoch.
	Ctime_ns        int64  // status change time; nanoseconds since epoch.
	Name            string // name of file as presented to Open.
	FollowedSymlink bool   // followed a symlink to get this information
}

A FileInfo describes a file and is returned by Stat, Fstat, and Lstat

func (*FileInfo) IsBlock 

func (f *FileInfo) IsBlock() bool

IsBlock reports whether the FileInfo describes a block special file.

func (*FileInfo) IsChar 

func (f *FileInfo) IsChar() bool

IsChar reports whether the FileInfo describes a character special file.

func (*FileInfo) IsDirectory 

func (f *FileInfo) IsDirectory() bool

IsDirectory reports whether the FileInfo describes a directory.

func (*FileInfo) IsFifo 

func (f *FileInfo) IsFifo() bool

IsFifo reports whether the FileInfo describes a FIFO file.

func (*FileInfo) IsRegular 

func (f *FileInfo) IsRegular() bool

IsRegular reports whether the FileInfo describes a regular file.

func (*FileInfo) IsSocket 

func (f *FileInfo) IsSocket() bool

IsSocket reports whether the FileInfo describes a socket. 

func (f *FileInfo) IsSymlink() bool

IsSymlink reports whether the FileInfo describes a symbolic link.

func (*FileInfo) Permission 

func (f *FileInfo) Permission() uint32

Permission returns the file permission bits.

type LinkError 

type LinkError struct {
	Op    string
	Old   string
	New   string
	Error Error
}

LinkError records an error during a link or symlink or rename system call and the paths that caused it.

func (*LinkError) String 

func (e *LinkError) String() string

type PathError 

type PathError struct {
	Op    string
	Path  string
	Error Error
}

PathError records an error and the operation and file path that caused it.

func (*PathError) String 

func (e *PathError) String() string

type ProcAttr 

type ProcAttr struct {
	// If Dir is non-empty, the child changes into the directory before
	// creating the process.
	Dir string
	// If Env is non-nil, it gives the environment variables for the
	// new process in the form returned by Environ.
	// If it is nil, the result of Environ will be used.
	Env []string
	// Files specifies the open files inherited by the new process.  The
	// first three entries correspond to standard input, standard output, and
	// standard error.  An implementation may support additional entries,
	// depending on the underlying operating system.  A nil entry corresponds
	// to that file being closed when the process starts.
	Files []*File
}

ProcAttr holds the attributes that will be applied to a new process started by StartProcess.

type Process 

type Process struct {
	Pid int
	// contains filtered or unexported fields
}

Process stores the information about a process created by StartProcess.

func (*Process) Kill 

func (p *Process) Kill() Error

Kill causes the Process to exit immediately.

func (*Process) Release 

func (p *Process) Release() Error

Release releases any resources associated with the Process.

func (*Process) Signal 

func (p *Process) Signal(sig Signal) Error

Signal sends a signal to the Process.

func (*Process) Wait 

func (p *Process) Wait(options int) (w *Waitmsg, err Error)

Wait waits for the Process to exit or stop, and then returns a Waitmsg describing its status and an Error, if any. The options (WNOHANG etc.) affect the behavior of the Wait call.

type Signal 

type Signal interface {
	String() string
}

A Signal can represent any operating system signal.

type SyscallError 

type SyscallError struct {
	Syscall string
	Errno   Errno
}

SyscallError records an error from a specific system call.

func (*SyscallError) String 

func (e *SyscallError) String() string

type UnixSignal 

type UnixSignal int32

func (UnixSignal) String 

func (sig UnixSignal) String() string

type Waitmsg 

type Waitmsg struct {
	Pid                int             // The process's id.
	syscall.WaitStatus                 // System-dependent status info.
	Rusage             *syscall.Rusage // System-dependent resource usage info.
}

Waitmsg stores the information about an exited process as reported by Wait.

func (Waitmsg) String 

func (w Waitmsg) String() string

Source Files

View all Source files

Directories

Path Synopsis
Package inotify implements a wrapper for the Linux inotify system.
 Package inotify implements a wrapper for the Linux inotify system.
Package signal implements operating system-independent signal handling.
 Package signal implements operating system-independent signal handling.
Package user allows user account lookups by name or id.
 Package user allows user account lookups by name or id.

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