golang os

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_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_SYNC int = syscall.O_SYNC // open for synchronous I/O. 不懂
 O_TRUNC int = syscall.O_TRUNC // if possible, truncate file when opened. 不懂 截短?什么?
)

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
)

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

var (
 ErrInvalid = errors.New("invalid argument")
 ErrPermission = errors.New("permission denied")
 ErrExist = errors.New("file already exists")
 ErrNotExist = errors.New("file does not exist")
)
错误类型
var (
 Stdin = NewFile(uintptr(syscall.Stdin), "/dev/stdin")
 Stdout = NewFile(uintptr(syscall.Stdout), "/dev/stdout")
 Stderr = NewFile(uintptr(syscall.Stderr), "/dev/stderr")
)
var Args []string
命令参数

 
func Chdir(dir string) error
改变工作目录
func Chmod(name string, mode FileMode) error
func Chown(name string, uid, gid int) error
相当于UNIX里面的命令

func Chtimes(name string, atime time.Time, mtime time.Time) error 

改变访问时间和修改时间

func Clearenv()
清除所有环境变量

func Environ() []string 
返回环境变量,以key=value的形式

func Exit(code int)
结束当前程序,非0表示错误

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

Expand replaces ${var} or $var in the string based on the mapping function. For example, os.ExpandEnv(s) is equivalent to os.Expand(s, os.Getenv).

func ExpandEnv(s string) string 

ExpandEnv replaces ${var} or $var in the string according to the values of the current environment variables. References to undefined variables are replaced by the empty string.

这两个函数不懂

func Getenv(key string) string 
获得key对应的环境变量

func Getegid() int 
返回当前用户有效的组id

func Geteuid() int 
返回该用户有效的id

func Getgid() int 
返回该用户的组id

func Getgroups() ([]int, error)
返回该用户属于的所有组

func Getpagesize() int 
这个也不懂

func Getpid() int 
返回调用者的进程id

func Getppid() int 
返回调用者上一级进程的进程id

func Getuid() int 
返回调用者的user id

func Getwd() (pwd string, err error)
返回什么不知道......

func Hostname() (name string, err error)
返回Host名通过kernel

func IsExist(err error) bool 
文件或目录是否存在

func IsNotExist(err error) bool 
文件和目录是否不存在

func IsPathSeparator(c uint8) bool
是否是文件划分符

func IsPermission(err error) bool 
是否该错误是权限不足

func Lchown(name string, uid, gid int) error 
如果有link只改link

func Link(oldname, newname string) error 
链接文件

func Mkdir(name string, perm FileMode) error 
创建目录,第二个参数估计是权限什么的

func MkdirAll(path string, perm FileMode) error 
创建目录,如果父目录没有的话也会创建,比如 /home/mike/parentepath/man.go

func NewSyscallError(syscall string, err error) error 
new 一个新的系统调用错误

func Readlink(name string) (string, error)
返回link的目的地

func Remove(name string) error 
移除文件或目录

func RemoveAll(path string) error 
path包含的所有也会删除

func Rename(oldname, newname string) error 
重命名文件

func SameFile(fi1, fi2 FileInfo) bool 
是否为同一文件

func Setenv(key, value string) error 
设置环境变量

func Symlink(oldname, newname string) error 
创建链接

func TempDir() string 
返回临时目录,就是那种重启了什么都会没有了的目录,比如linux里面的tmp

func Truncate(name string, size int64) error 
截取文件,如果是链接,截取链接的目标

 15 // File represents an open file descriptor.
 16 type File struct {
 17 *file
 18 }
 19 
 20 // file is the real representation of *File.
 21 // The extra level of indirection ensures that no clients of os
 22 // can overwrite this data, which could cause the finalizer
 23 // to close the wrong file descriptor.
 24 type file struct {
 25 fd int
 26 name string
 27 dirinfo *dirInfo // nil unless directory being read
 28 nepipe int32 // number of consecutive EPIPE in Write
 29 }

func Create(name string) (file *File, err error)
创建文件
func NewFile(fd uintptr, name string) *File
根据文件描述符来创建文件
func Open(name string) (file *File, err error)
打开文件只读
func OpenFile(name string, flag int, perm FileMode) (file *File, err error)
打开文件,specified flag (O_RDONLY etc.) and perm, (0666 etc.) 以相应的权限和标记打开
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.
 建立一根管道
func (f *File) Chdir() error
改变working目录到f所在的目录,必须是一个目录
func (f *File) Chmod(mode FileMode) error
 Chmod changes the mode of the file to mode. If there is an error, it will be of type *PathError.
func (f *File) Chown(uid, gid int) error
 Chown changes the numeric uid and gid of the named file. If there is an error, it will be of type *PathError.
 不解释
func (f *File) Close() error
打开文件记得 defer f.Close()
func (f *File) Fd() uintptr
返回文件描述符
func (f *File) Name() string
返回文件名
func (f *File) Read(b []byte) (n int, err error)
 It returns the number of bytes read and an error, if any. EOF is signaled by a zero count with err set to io.EOF.
 读取缓冲大小的数据(b是切片,实际上就是一个指针)
func (f *File) ReadAt(b []byte, off int64) (n int, err error)
读取从off开始的数据
func (f *File) Readdir(n int) (fi []FileInfo, err error)
func (f *File) Readdirnames(n int) (names []string, err error)
读取目录下的文件,一个要得到info一个要得到名字,n表示的是小于0读取全部,大于0就读取到n个
func (f *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.
 offst偏移量,whence 0 表示从原始位置算, whence 1表示从当前位置算,whence2表示从末尾算(话说这个直接用数字来代表相对位置很奇怪......)
func (f *File) Stat() (fi FileInfo, err error)
返回文件信息
func (f *File) Sync() (err error)
把现有的文件内容存入稳定的存储区域,一般是磁盘
func (f *File) Truncate(size int64) error
改变文件大小
func (f *File) Write(b []byte) (n int, err error)
写文件
func (f *File) WriteAt(b []byte, off int64) (n int, err error)
偏移地写文件
func (f *File) WriteString(s string) (ret int, err error)
写字符串

type FileInfo interface {
 Name() string // base name of the file
 Size() int64 // length in bytes for regular files; system-dependent for others
 Mode() FileMode // file mode bits
 ModTime() time.Time // modification time
 IsDir() bool // abbreviation for Mode().IsDir()
 Sys() interface{} // underlying data source (can return nil)
}

type FileMode uint32
A FileMode represents a file's mode and permission bits. The bits have the same definition on all systems, so that information about files can be moved from one system to another portably. Not all bits apply to all systems. The only required bit is ModeDir for directories.
const (
 // The single letters are the abbreviations
 // used by the String method's formatting.
 ModeDir FileMode = 1 << (32 - 1 - iota) // d: is a directory
 ModeAppend // a: append-only
 ModeExclusive // l: exclusive use
 ModeTemporary // T: temporary file (not backed up)
 ModeSymlink // L: symbolic link
 ModeDevice // D: device file
 ModeNamedPipe // p: named pipe (FIFO)
 ModeSocket // S: Unix domain socket
 ModeSetuid // u: setuid
 ModeSetgid // g: setgid
 ModeCharDevice // c: Unix character device, when ModeDevice is set
 ModeSticky // t: sticky
 // Mask for the type bits. For regular files, none will be set.
 ModeType = ModeDir | ModeSymlink | ModeNamedPipe | ModeSocket | ModeDevice
 ModePerm FileMode = 0777 // permission bits
)

进程属性
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
 // Operating system-specific process creation attributes.
 // Note that setting this field means that your program
 // may not execute properly or even compile on some
 // operating systems.
 Sys *syscall.SysProcAttr
}

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