Wildcard Names

1. Wildcard Names
   1. Description
   2. Directory By Directory Vs Recursive Wildcards
   3. Bucket Wildcards
   4. Other Wildcard Characters
   5. Potentially Surprising Behavior When Using Wildcards
   6. Different Behavior For "Dot" Files In Local File System
   7. Efficiency Consideration: Using Wildcards Over Many Objects
   8. Efficiency Consideration: Using Mid-Path Wildcards

Wildcard Names

Description

gsutil supports URI wildcards. For example, the command:

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

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

Directory By Directory Vs Recursive Wildcards

The "*" wildcard only matches up to the end of a path within a subdirectory. For example, if bucket contains objects named gs://bucket/data/abcd, gs://bucket/data/abcdef, and gs://bucket/data/abcxyx, as well as an object in a sub-directory (gs://bucket/data/abc/def) the above gsutil cp command would match the first 3 object names but not the last one.

If you want matches to span directory boundaries, use a '**' wildcard:

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

will match all four objects above.

Note that gsutil supports the same wildcards for both objects and file names. Thus, for example:

gsutil cp data/abc* gs://bucket

will match all names in the local file system. Most command shells also support wildcarding, so if you run the above command probably your shell is expanding the matches before running gsutil. However, most shells do not support recursive wildcards ('**'), and you can cause gsutil's wildcarding support to work for such shells by single-quoting the arguments so they don't get interpreted by the shell before being passed to gsutil:

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

Bucket Wildcards

You can specify wildcards for bucket names within a single project. For example:

gsutil ls gs://data*.example.com

will list the contents of all buckets whose name starts with "data" and ends with ".example.com" in the default project. The -p option can be used to specify a project other than the default. For example:

gsutil ls -p other-project gs://data*.example.com

You can also combine bucket and object name wildcards. For example this command will remove all ".txt" files in any of your Cloud Storage buckets in the default project:

gsutil rm gs://*/**.txt

Other Wildcard Characters

In addition to '*', you can use these wildcards:

?

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

Potentially Surprising Behavior When Using Wildcards

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

1. 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 will treat "#" as a special character, which conflicts with that character's use in referencing versioned objects (see gsutil help versions for details).

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

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

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

   will cause 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 will copy all objects from gs://bucket1 to gs://bucket2:

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

but the following command will copy 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 will perform 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 will be. 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 will match 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 will list the entire bucket and filter locally, so that could require a non-trivial amount of network traffic).