Wildcard Names

Description

gsutil supports URI wildcards for files, buckets, and objects. For example, the command:

gsutil cp gs://bucket/data/abc* .

copies all objects that start with gs://bucket/data/abc followed by any number of characters within that subdirectory.

Wildcard Characters

gsutil uses the following wildcards:

*
Match any number of characters within the current directory level. For example, gs://my-bucket/abc/d* matches the objectabc/def.txt but not the object abc/def/g.txt.
**
Match any number of characters across directory boundaries. When used as part of a local file path, the ** wildcard should always be immediately preceded by a directory delimiter. For example, my-directory/**.txt is valid, but my-directory/abc** is not.
?
Match a single character. For example gs://bucket/??.txt only matches objects with two characters followed by .txt.
[chars]
Match any of the specified characters. For example gs://bucket/[aeiou].txt matches objects that contain a single vowel character followed by .txt.
[char range]
Match any of the range of characters. For example gs://bucket/[a-m].txt matches objects that contain letters a, b, c, ... or m, and end with .txt.

You can combine wildcards to provide more powerful matches, for example:

gs://*/[a-m]??.j*g

Note that unless your command includes a flag to return noncurrent object versions in the results, these wildcards only match live object versions.

gsutil supports the same wildcards for both object and file names. Thus, for example:

gsutil cp data/abc* gs://bucket

matches all files that start with abc in the data directory of the local file system.

Potentially Surprising Behavior When Using Wildcards

There are a couple of ways that using wildcards can result in surprising behavior:

  1. When using wildcards in bucket names, matches are limited to buckets in the project specified in the -p flag. Some commands, such as gsutil rm, do not support the -p flag. If the -p flag is not or cannot be used in a command, matches are limited to buckets in the default project.

  2. Shells (like bash and zsh) can attempt to expand wildcards before passing the arguments to gsutil. If the wildcard was supposed to refer to a cloud object, this can result in surprising "Not found" errors (e.g., if the shell tries to expand the wildcard gs://my-bucket/* on the local machine, matching no local files, and failing the command).

    Note that some shells include additional characters in their wildcard character sets. For example, if you use zsh with the extendedglob option enabled it treats # as a special character, which conflicts with that character's use in referencing versioned objects (see Restore noncurrent object versions for an example).

    To avoid these problems, surround the wildcarded expression with single quotes (on Linux) or double quotes (on Windows).

  3. Attempting to specify a filename that contains wildcard characters won't work, because gsutil tries to expand the wildcard characters rather than using them as literal characters. For example, running the command:

    gsutil cp './file[1]' gs://my-bucket
    

    causes gsutil to try to match the [1] part as a wildcard.

    There's an open issue to support a "raw" mode for gsutil to provide a way to work with file names that contain wildcard characters, but until / unless that support is implemented there's no really good way to use gsutil with such file names. You could use a wildcard to name such files, for example replacing the above command with:

    gsutil cp './file*1*' gs://my-bucket
    

    but that approach may be difficult to use in general.

Different Behavior For "Dot" Files In Local File System

Per standard Unix behavior, the wildcard * only matches files that don't start with a . character (to avoid confusion with the . and .. directories present in all Unix directories). gsutil provides this same behavior when using wildcards over a file system URI, but does not provide this behavior over cloud URIs. For example, the following command copies all objects from gs://bucket1 to gs://bucket2:

gsutil cp gs://bucket1/* gs://bucket2

but the following command copies only files that don't start with a . from the directory dir to gs://bucket1:

gsutil cp dir/* gs://bucket1

Efficiency Consideration: Using Wildcards Over Many Objects

It is more efficient, faster, and less network traffic-intensive to use wildcards that have a non-wildcard object-name prefix, like:

gs://bucket/abc*.txt

than it is to use wildcards as the first part of the object name, like:

gs://bucket/*abc.txt

This is because the request for gs://bucket/abc*.txt asks the server to send back the subset of results whose object name start with abc at the bucket root, and then gsutil filters the result list for objects whose name ends with .txt. In contrast, gs://bucket/*abc.txt asks the server for the complete list of objects in the bucket root, and then filters for those objects whose name ends with abc.txt. This efficiency consideration becomes increasingly noticeable when you use buckets containing thousands or more objects. It is sometimes possible to set up the names of your objects to fit with expected wildcard matching patterns, to take advantage of the efficiency of doing server-side prefix requests. See, for example gsutil help prod for a concrete use case example.

Efficiency Consideration: Using Mid-Path Wildcards

Suppose you have a bucket with these objects:

gs://bucket/obj1
gs://bucket/obj2
gs://bucket/obj3
gs://bucket/obj4
gs://bucket/dir1/obj5
gs://bucket/dir2/obj6

If you run the command:

gsutil ls gs://bucket/*/obj5

gsutil performs a /-delimited top-level bucket listing and then one bucket listing for each subdirectory, for a total of 3 bucket listings:

GET /bucket/?delimiter=/
GET /bucket/?prefix=dir1/obj5&delimiter=/
GET /bucket/?prefix=dir2/obj5&delimiter=/

The more bucket listings your wildcard requires, the slower and more expensive it becomes. The number of bucket listings required grows as:

  • the number of wildcard components (e.g., "gs://bucket/a??b/c*/*/d" has 3 wildcard components);
  • the number of subdirectories that match each component; and
  • the number of results (pagination is implemented using one GET request per 1000 results, specifying markers for each).

If you want to use a mid-path wildcard, you might try instead using a recursive wildcard, for example:

gsutil ls gs://bucket/**/obj5

This matches more objects than gs://bucket/*/obj5 (since it spans directories), but is implemented using a delimiter-less bucket listing request (which means fewer bucket requests, though it lists the entire bucket and filters locally, so that could require a non-trivial amount of network traffic).