[Golang] Filename Globbing Summary

Filename globbing are found in several places in Go standard library.

• filepath.Glob
• filepath.Match
• path.Match
• template.ParseGlob

I want to how the it works, so I use a small example to test. I have the two txt files as follows:

testdir/a.txt
textdir/subdir/b.txt

Use testdir/*.txt as pattern in filepath.Glob:

package main

import (
      "path/filepath"
      "fmt"
)

func main() {
      matches, err := filepath.Glob("testdir/*.txt")
      if err != nil {
              panic(err)
      }

      fmt.Println(matches)
}

The output:

[testdir/a.txt]

As expected, * does not match sub-directory. How about **? Modify the pattern from testdir/*.txt to testdir/**.txt, and the output is:

[testdir/a.txt]

The output is the same. ** does not match zero or more directories [3].

If sub-directory depth is known, we can still match file in sub-directory. For example, modify the pattern from testdir/*.txt to testdir/*/*.txt [4]. The output is:

[testdir/subdir/b.txt]

The file in sub-directory is matched.

My summary

• * does not match sub-directories.
• ** is not supported, i.e., does not match zero or more directories.
• If depth of sub-directories is known, sub-directories can be matched with workaround.
• There are third-party packages which provides more complete glob features [5].

Tested on:

• Ubuntu Linux 17.04
• Go 1.8.1

References: