Golang : Append content to a file



Tags : golang append

In this tutorial, we will learn how to open a file with specific mode such as for appending data when writing. This means that the operation depends on how the file is opened initially. Example of appending content to a file : appendfile.go package main import ( "os" "fmt" ) func main () { // open files r and w file, err := os.OpenFile("input.txt", os.O_APPEND|os.O_WRONLY,0600) if err != nil { panic(err) defer file.Close() if _, err = file.WriteString(" this is the APPENDED text"); err != nil { panic(err) fmt.Printf("Appended into file\n") There is a reference at the page bottom on what os.O_APPEND and os.O_WRONLY parameters about. Reference : Extract from http://golang.org/src/pkg/os/file.go // Flags to Open wrapping those of the underlying system. Not all flags // may be implemented on a given system. 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. O_TRUNC int = syscall.O_TRUNC // if possible, truncate file when opened. )


Tags : golang append

By Adam Ng

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