Labels

Contents

Overview
Why Not Just Use Changelist Numbers?
Creating a Label
Adding and Changing Files Listed in a Label
Preventing Accidental Overwrites of a Label's Contents
Retrieving a Label's Contents into a Client Workspace
Deleting Labels
Label Reporting

Overview
A Perforce label is a user-determined list of files and revisions. The label can later be used to reproduce the state of these files within a client workspace.
Labels provide a method of naming important combinations of file revisions for later reference. For example, the file revisions that comprise a particular release of your software might be given the label release2.0.1. At a later time, you can retrieve all the files in that label into a client workspace with a single command.
Create a label when:

You want to keep track of all the file revisions contained in a particular release of the software,

There exists a particular set of file revisions that you want to give to other users, or

You have a set of file revisions that you want to branch from, but you don't want to perform the branch yet. In this case, you would create a label for the file revisions that will form the base of the branch.

Why Not Just Use Changelist Numbers?
Labels share certain important characteristics with change numbers, as both refer to particular file sets, and both act as handles to refer to all the files in the set. But labels have some important advantages over change numbers:

The file revisions referenced by a particular label can come from different changelists.

A change number refers to the state of all the files in the depot at the time the changelist was submitted, while a label can refer to any arbitrary set of files and revisions.

The files and revisions referenced by a label can be arbitrarily changed at any point in the label's existence.

Changelists are always referred to by Perforce-assigned numbers, while labels are named by the user.

Creating a Label
You can create a label with p4 label labelname. This command brings up a form similar to the p4 client form. Like clients, labels have associated views; the label view limits which files can be referenced by the label. Once you have created the label, use p4 labelsync to load the label with file references.
Label names share the same namespace as clients, branches, and depots. Thus, a label name cannot be the same as any existing client, branch, or depot name.

Example: Creating a Label
Ed has finished the first version of filtering in elm. He wants to create a label that references only those files in the filter and hdrs subdirectories. He wants to name the label filters.1. He types p4 label filters.1 and fills in the resulting form as follows:
    Label:  filters.1
    Owner:  edk
    Description:
            Created by edk.
    Options:        unlocked
    View:
            //depot/elm_proj/filter/...
            //depot/elm_proj/hdrs/...
When he quits from the editor, the label is created.
Before following this example further, it's worth stopping for a moment to examine exactly what has and hasn't been accomplished. So far, a label called filters.1 has been created. It can contain files only from the depot's elm_proj filter and hdrs subdirectories. But the label filters.1 is empty; it contains no file references. It will be loaded with its file references with p4 labelsync.
The View: field limits the files that are included in the label. These files must be specified by their location in the depot; this view differs from other views in that only the depot side of the view is specified.
The locked / unlocked option in the Options: field can prevent p4 labelsync from overwriting previously synced labels (this is described in "Preventing Accidental Overwrites of a Label's Contents" on page 88).

Adding and Changing Files Listed in a Label
Once you've created a label, you can include references to files within it by using p4 labelsync. This command's syntax is

p4 labelsync [-a -d -n] -l labelname [filename...]

The rules followed by labelsync to include files in a label are as follows:
You must be the owner of the label in order to use p4 labelsync on it, and the label must be unlocked.

If you are not the owner of a label, you may (assuming you have sufficient permissions) make yourself the owner by running:

p4 label labelname

and changing the Owner: field to your userid in the p4 label form. Similarly, you may unlock a label by setting the Options: field (also in the p4 label form) to unlocked.

All files listed in a label must be contained in the label view specified in the p4 label form. Any files or directories that are not mapped through the label view are ignored by p4 labelsync. All the following rules assume this, without further mention.

When p4 labelsync is used to include a particular file in a label's file list, the file is added to the label if it is not already included in the label. If a different revision of the file is already included in the label's file list, it is replaced with the newly specified revision. Only one revision of any file is ever included in a label's file list.
If labelsync is called with no filename arguments, as in:

p4 labelsync -l labelname

then all the files mapped by the label view are listed in the label. The revisions added to the label are those last synced into the client; these revisions can be seen in the p4 have list. Calling p4 labelsync this way replaces all existing file references with the new ones.

Example: Including file references in a label with p4 labelsync.
Ed has created a label called filters.1 as specified above, and now he wants to load the filters.1 label with the proper file revisions. He types:

p4 labelsync -l filters.1

and sees the following:
    //depot/elm_proj/filter/Makefile.SH#20 - added
    //depot/elm_proj/filter/actions.c#25 - added
    <etc.>
Perforce adds those file revisions to the label that are those contained in the intersection of the label view and the current client have list.
When you call p4 labelsync with file pattern arguments, and the arguments contain no revision specifications, the head revisions of these files are included in the label's file list.

Example: Changing file references in a label with p4 labelsync.
After performing the above labelsync command, Ed finds that the file filter/filter.c is buggy. He fixes it, submits the new version, and wants to replace the old revision of this file in the label filters.1 with the new revision. From the filter subdirectory, he types
p4 labelsync -l filters.1 filter/filter.c

and sees
 //depot/elm_proj/filter/filter.c#15 - updated
The head revision of filter.c replaces the revision that had been previously included in the label.
If you call p4 labelsync with file pattern arguments containing revision specifications, these file revisions are included in the label's file list.

Example: Including a different file revision in a label
Ed realizes that the version of filter/audit.c contained in his label filters.1 is not the version he wants to include in the label. He'd prefer to include revision 12 of that file. From the main Elm directory, he types
p4 labelsync -l filters.1 filter/audit.c#12

and sees:
    /depot/elm_proj/filter/audit.c#12 - updated
This revision of audit.c replaces the revision that had been previously included in the label.
Previewing labelsync's results
The results of p4 labelsync can be previewed with p4 labelsync -n. This lists the files that would be added, deleted, or replaced in the label without actually performing the operation.

Preventing Accidental Overwrites of a Label's Contents
Since p4 labelsync with no file arguments overwrites all the files that are listed in the label, it is possible to accidentally lose the information that a label is meant to contain. To prevent this, call p4 label labelname and set the value of the Options: field to locked. It will be impossible to call p4 labelsync on that label until the label is subsequently unlocked.

Retrieving a Label's Contents into a Client Workspace
To retrieve all the files listed in a label into a client workspace, use p4 sync files@labelname. Rather than simply adding the files to the client workspace, this command matches the state of the client workspace to the state of the label. Thus, files in the client workspace that aren't in the label may be deleted from the client workspace.

Example: Retrieving files into a client workspace from a label.
Lisa wants to retrieve all the files listed in Ed's filters.1 label into her client workspace. She can type:
p4 sync //depot/...@filters.1

or even:
p4 sync @filters.1

Instead, she's interested in seeing only the header files from that label, so she types:
p4 sync //depot/elm_proj/hdrs/*@filters.1

and sees:
    //depot/elm_proj/hdrs/curses.h#1 - added as /usr/lisag/elm/hdrs/curses.h
    //depot/elm_proj/hdrs/defs.h#1 - added as /usr/lisag/elm/hdrs/defs.h
    //depot/elm_proj/hdrs/test.h#3 - deleted as /usr/lisag/elm/hdrs/test.h
    <etc>
All the files in the subdirectory hdrs that are within the intersection of Ed's filters.1 label and Lisa's client view are retrieved into her workspace. But there is another effect as well: files that are not in the intersection of the label's contents and //depot/elm_proj/hdrs/* are deleted from her workspace.
If p4 sync @labelname is called with no file parameters, all files in the client that are not in the label will be deleted from the client. If this command is called with file arguments, as in p4 sync files@labelname, then the client workspace at the intersection of the depot, the client workspace view, and the file arguments will be updated to match the contents of the depot at that intersection.

Deleting Labels
You can delete a label with:

p4 label -d labelname
You can delete files from labels with:

p4 labelsync -d -l labelname filepattern
To delete all the files from the label's file list, but leave the empty label in the Perforce database, use:

p4 labelsync -d -l labelname

Label Reporting
The commands that provide reports on labels are:

Command Description
p4 labels Report the names, dates, and descriptions of all labels known to the server
p4 labels file#revrange Report the names, dates, and descriptions of all labels that include the specified revision range of file.
p4 files @labelname Lists all files and revisions contained in the given label.
p4 sync -n @labelname Shows what p4 sync would do when retrieving files from a particular label into your client workspace, without actually performing the sync.

Command	Description
p4 labels	Report the names, dates, and descriptions of all labels known to the server
p4 labels file#revrange	Report the names, dates, and descriptions of all labels that include the specified revision range of file.
p4 files @labelname	Lists all files and revisions contained in the given label.
p4 sync -n @labelname	Shows what p4 sync would do when retrieving files from a particular label into your client workspace, without actually performing the sync.