Using the OS to complete file operations (common)

Need to use Golang to complete a program to write to the file, the first time to use these functions under the OS, give yourself a document. Look at the source of the process, found using Golang file creation functions, need to understand the knowledge of the file permission bit (Ps:java has never been a method to solve, never carefully understand), here to put a [explanation of the Authority bit] (https://blog.csdn.net/ devyfong/article/details/8066369) 's blog. I use the IDE is IntelliJ Goland, see the source is very convenient, recommend and I like beginners use # # func getwd (dir string, err Error) {...} Get the program run path, equivalent to running ' pwd ' command '//code package Mainimport ("FMT" "OS") Func main () {FMT] under Linux. Println (OS. GETWD ())}//command line execution bogon:postback zhaoyf$ go run application.go/users/zhaoyf/code/go_path/src/adr-postback-consumer/ Postback <nil>bogon:postback zhaoyf$ CD ~bogon:~ zhaoyf$ go run code/go_path/src/adr-postback-consumer/postback/ Application.go/users/zhaoyf <nil> ' # # # func isnotexist (err error) bool {...} Determine if err is not present in the hint file or directory "//-----Source//Error.go-isnotexist () Func isnotexist (err error) bool {return isnotexist (err)}// Error_unix.go-Isnotexist ()//My environment is Mac, possibly other system file names are different func isnotexist (err error) bool {err = Underlyingerror (ERR)//Contemporary Code See this step to find out that this method is used to compare the parameter err is not a specified error return err = = Syscall. ENOENT | | Err = = Errnotexist}//Error.go-Underlyingerror ()//returns the underlying error of the known OS error type Func underlyingerror (err Error) error {switch err: = Err. (type) {Case *patherror:return err. Errcase *linkerror:return Err. Errcase *syscallerror:return Err. Err}return err} ' # # # func Mkdir (name string, perm FileMode) error {...} Creates a folder based on the given path [name] and specifies the folder's permissions through Perm "///self-Encapsulated Create folder function func mkdir (path string) {err: = OS. Mkdir (Path, OS. MODEDIR)//When error is returned and error is not a file that already exists errors, print the wrong message if err! = Nil && os. Isnotexist (Err) {FMT. Printf ("[init] Create log dir[%s] falied:%s\n", Path, Err)}} ' # # func OpenFile (name string, flag int, perm FileMode) (* File, error) {...} Return a method that can perform I/O operations, read and write by the *file of the operation return value, note that the release of the stream resources "//the specific constant code length is too long, please look for your own//flag value as shown below see File.go-65 Row constant definition//Perm value See Types.go, 42 Line Constants Definition ' # # # func-Create (name string) (*file, error) {...} Do not explain, directly look at the source bar "" Func Create (name string) (*file, error) {//If the o_* constant is not understood, you can see the OpenFile () function above the flag value return OpenFile (name, o_rdwr| o_create| O_trunc, 0666)} ' ' # # # func (f *file) WRite (b []byte) (n int, err error) {...} Writes the file, returns the number of bytes written successfully "//Steal a lazy, example directly affixed writestring () function of the source//writestring is like Write, but writes the contents of string s rather than//a slice of Bytes.func (f *file) WriteString (s string) (n int, err error) {return F.write ([]byte (s))}//the written text of your own encapsulated letter Number of Func write (log string, FilePath string) {file, err: = OS. OpenFile (FilePath, OS. O_wronly|os. O_create|os. O_append, 0666) if err! = Nil && os. Isnotexist (Err) {FMT. Printf ("[Write] Create log file[%s] falied:%s\n", FilePath, Err)}defer file. Close () file. WriteString (log + "\ n")} ' # # # OS. PathSeparator Add a small egg, file path delimiter, win with ' \ \ ' Unix with '/', in order to avoid writing in the code of the bug caused by death, you can use this constant instead of 83 clicks