Package os provides a platform-independent interface to operating system functionality. The design is Unix-like, although the error handling is Go-like; failing calls return values of type error rather than error numbers. Often, more information is available within the error. For example, if a call that takes a file name fails, such as [Open] or [Stat], the error will include the failing file name when printed and will be of type [*PathError], which may be unpacked for more information.

The os interface is intended to be uniform across all operating systems. Features not generally available appear in the system-specific package syscall.

Here is a simple example, opening a file and reading some of it.

 file, err := os.Open("file.go") // For read access.
 if err != nil {
   log.Fatal(err)
 }
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If the open fails, the error string will be self-explanatory, like

 open file.go: no such file or directory
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The file's data can then be read into a slice of bytes. Read and Write take their byte counts from the length of the argument slice.

 data := make([]byte, 100)
 count, err := file.Read(data)
 if err != nil {
   log.Fatal(err)
 }
 fmt.Printf("read %d bytes: %q\n", count, data[:count])
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Concurrency

The methods of [File] correspond to file system operations. All are safe for concurrent use. The maximum number of concurrent operations on a File may be limited by the OS or the system. The number should be high, but exceeding it may degrade performance or cause other issues.