Perforce 98.2: Basics: The Details

Perforce 98.2 p4 User's Guide


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Chapter 4
Perforce Basics: The Details

The Quick Start chapter explained the basics of using Perforce, but discussion of the practical details was deferred. This chapter, which supplements the Quick Start chapter, covers the dry Perforce rules. The topics discussed include views, mapping depots to client workspaces, Perforce wildcards, rules for referring to older file revisions, file types, and form syntax.

It is assumed that the material in the Quick Start chapter has been read and properly digested.

Description of the Client Workspace

A Perforce client workspace is a collection of source files managed by Perforce on a host. Each such collection is given a name which identifies the client workspace to the Perforce server. The name is by default simply the host's name but that can be overridden by the environment variable P4CLIENT. There can be more than one Perforce client workspace on a client host.

All files within a Perforce client workspace share a common root directory, called the client root. In the degenerate case, the client root can be the host's root, but in practice the client root is the lowest level directory under which the managed source files will sit.

Perforce manages the files in a client workspace in a few direct ways. It creates, updates, or deletes files when the user requests Perforce to synchronize the client workspace with the depot; it turns on write permission when the user requests to edit a file; and turns off write permission and submits updated versions back to the depot when the user is finished editing the file.

The entire Perforce client workspace state is tracked by the Perforce server. The server knows what files a client workspace has, where they are, and which files have write permission turned on.

Perforce's management of a client workspace requires a certain amount of cooperation from the user. Since client files are just plain files with write permission turned off, willful users can circumvent the system by turning on write permission, directly deleting or renaming files, or otherwise modifying the file tree supposedly under Perforce's control. Perforce counters this with two measures: first, Perforce has explicit commands to verify that the client workspace state is in accord with the server's recording of that state; second, Perforce tries to make using Perforce at least as easy as circumventing it. For example: to make a temporary modification to a file, it is easier to use Perforce than it is to copy and restore the file manually.

Files not managed by Perforce may also be under a client's root, and they are largely ignored by Perforce. For example, Perforce may manage the source files in a client workspace, while the workspace also holds compiled objects, libraries, executables, as well as a developer's temporary files.

In addition to accessing the client files, the p4 client program sometimes creates temporary files on the client host. Otherwise, Perforce neither creates nor uses any files on the client host.

Wildcards

Perforce uses three wildcards for pattern matching. Any number and combination of these can be used in a single string:


Wildcard	Meaning
`*`	Matches anything except slashes, matches only within a single directory.
`...`	Matches anything including slashes; matches across multiple directories
`%d`	Used for parametric substitution in views. Details are provided further down.

The "..." wildcard is passed by the p4 client program to the p4d server, where it is expanded to match the corresponding files known to p4d. The * wildcard is expanded locally by the OS shell before the p4 command is sent to the server, and the files that match the wildcard are passed as multiple arguments to the p4 command. To have Perforce match the * wildcard against the contents of the depot, it must be escaped, usually with quotes or a backslash. Most command shells don't interfere with the other two wildcards.

Wildcards and `p4 add'

There is one case in which the "..." wildcard cannot be used, and that is with the p4 add command. The "..." wildcard is expanded by the p4d server, and since the server doesn't know what files are being added (after all, they're not in the depot yet), it can't expand that wildcard. The * wildcard can be used with p4 add; in this case, it is expanded by the local OS shell, not by the p4d server.

Mapping the Depot to the Client Workspace

Just as a client name is nothing more than an alias for a particular directory on the client machine, a depot name is an alias for a directory on the Perforce server. The relationship between files in the depot and files in the client workspace is described in the client view, and it is set with the p4 client command. When p4 client is typed, a variation of the following form is displayed:


`Client: eds_elm` `Owner: edk` `Description:` `Created by ed.` `Root: /usr/edk/elm` `Options: nomodtime noclobber` `View:` `//depot/... //eds_elm/...`

The contents of the View: field determine where client files get stored in the depot, and where depot files are copied to in the client.

Using Views

95/98/NT

On Windows machines, the Perforce client workspace must be specified in a slightly different format if it is to span multiple drives. For details, please see the release notes, which are available at our website.

Views consist of multiple lines, or mappings, and each mapping has two parts. The left-hand side specifies one or more files within the depot, and has the form

//depotname/file_specification

The right-hand side of each mapping describes one or more files within the client workspace, and has the form

//clientname/file_specification

The left-hand side of a client view mapping is called the depot side; the right-hand side is the client side.

The default view in the example above is quite simple: it maps the entire depot to the entire client workspace. But views can contain multiple mappings, and can be much more complex. Any client view, no matter how elaborate, performs the same two functions:

The client view determines which files in the depot can be seen by a client workspace. This is determined by the sum of the depot sides of the mappings within a view. A view might allow the client workspace to retrieve every file in the depot, or only those files within two directories, or only a single file.
It constructs a one-to-one mapping between files in the depot and files in the client workspace. Each mapping within a view describes a subset of the complete mapping. The one-to-one mapping might be straightforward; for example, the client workspace file tree might be identical to a portion of the depot's file tree. Or it can be oblique; for example, a file might have one name in the depot and another in the client workspace, or be moved to an entirely different directory in the client workspace. No matter how the files are named, there is always a one-to-one mapping.

To determine the exact location of any client file on the host machine, substitute the value of the p4 client form's Root: field for the client name on the client side of the mapping. For example, if the p4 client form's Root: field for the client eds_elm is set to /usr/edk/elm, then the file //eds_elm/doc/elm-help.1 will be found on the client host in /usr/edk/elm/doc/elm-help.1.

Wildcards in Views

Any wildcard used on the depot side of a mapping must be matched with an identical wildcard in the mapping's client side. Any string matched by the wildcard will be identical on both sides.

In the client view

//depot/elm_proj/... //eds_elm/...

the single mapping contains Perforce's "..." wildcard, which matches everything, including slashes. The result is that any file in the eds_elm client workspace will be mapped to the same location within the depot's elm_proj file tree. For example, the file //depot/elm_proj/nls/gencat/README will be mapped to the client workspace file //eds_elm/nls/gencat/README.

Types of Mappings

By changing the View field, it's possible to map only part of a depot to a client workspace. It's even possible to map files within the same depot directory to different client workspace directories, or to have files named differently in the depot and the client workspace. This section discusses Perforce's mapping methods.

Direct Client-to-Depot Views

The default view in the form presented by p4 client maps the entire client workspace tree into an identical directory tree in the depot. For example, the default view

//depot/... //eds_elm/...

indicates that any file in the directory tree under the client eds_elm will be stored in the identical subdirectory in the depot. This view is usually considered to be overkill; most users only need to see a subset of the files in the depot.

Mapping the Full Client to only Part of the Depot

Usually only a portion of the depot is of interest to a particular client. The left-hand side of the View field can be changed to point to only the portion of the depot that's relevant.

Example

Mapping part of the depot to the client workspace.

Bettie is rewriting the documentation for Elm, which is found in the depot within its docsubdirectory. Her client is named elm_docs, and her client root is /usr/bes/docs; she types p4 client and sets the View field as follows:

//depot/elm_proj/doc/... //elm_docs/...

Mapping Files in the Depot to a Different Part of the Client

Views can consist of multiple mappings, which are used to map portions of the depot file tree to different parts of the client file tree. If there is a conflict in the mappings, later mappings have precedence over the earlier ones.

Example

Multiple mappings in a single client view.

The elm_proj subdirectory of the depot contains a directory called doc, which has all the Elm documents. Included in this directory are four files named elm-help.0 through elm-help.3. Mike wants to separate these four files from the other documentation files in his client workspace, which is called mike_elm.

To do this, he creates a new directory in his client workspace called help; it's located at the same level as his doc directory. The four elm-help files will go here; he fills in the View field of the p4 client form as follows:

//depot/... //mike_elm/...
//depot/elm_proj/doc/elm-help.* //mike_elm/help/elm-help.*

Any file whose name starts with elm-help within the depot's doc subdirectory will be caught by the later mapping and appear in Mike's workspace's help directory; all other files are caught by the first mapping and will appear in their normal location. Conversely, any files beginning with elm-help within Mike's client workspace help subdirectory will be mapped to the doc subdirectory of the depot.

Excluding Files and Directories from the View

Exclusionary mappings allow files and directories to be excluded from a client workspace; this is accomplished by prefacing the mapping with a minus sign ( - ). Whitespace is not allowed between the minus sign and the mapping.

Example

Using views to exclude files from a client workspace.

Bill, whose client is named billm, wants to view only source code; he's not interested in the documentation files. His client view would look like this:

//depot/elm_proj/... //billm/...
-//depot/elm_proj/doc/... //billm/doc/...

Since later mappings have precedence over earlier ones, no files from the depot's doc subdirectory will ever be copied to Bill's client. Conversely, if Bill does have a doc subdirectory in his client, no files from that subdirectory will ever be copied to the depot.

Allowing Filenames in the Client to be Different than Depot Filenames

Mappings can be used to make the names of files different in the client workspace than they are in the depot.

Example

Files with different names in the depot and client workspace.

Mike wants to store the files as above, but he wants to take the elm-help.X files in the depot and call them helpfile.X in his client workspace. He uses the following mappings:

//depot/elm_proj... //mike_elm/...
//depot/elm_proj/doc/elm-help.* //mike_elm/help/helpfile.*

Each wildcard on the depot side of a mapping must have a corresponding wildcard on the client side of the same mapping. The wildcards are replaced in the copied-to direction by the substring that the wildcard represents in the copied-from direction.

There can be multiple wildcards; the n-th wildcard in the depot specification corresponds to the n-th wildcard in the client description.

Changing the Order of Filename Substrings

The %d wildcard matches strings similarly to the * wildcard, but %d can be used to rearrange the order of the matched substrings.

Example

Changing string order in client workspace names.

Mike wants to change the names of any files with a dot in them within his doc subdirectory in such a way that the file's suffixes and prefixes are reversed in his client workspace. For example, he'd like to rename the Elm.cover file in the depot cover.Elm in his client workspace. (Mike can be a bit difficult to work with). He uses the following mappings:

//depot/elm_proj/... //mike_elm/...
//depot/elm_proj/doc/%1.%2 //mike_elm/doc/%2.%1

Two Mappings Can Conflict and Fail

It is possible for multiple mappings in a single view to lead to a situation in which the name does not map the same way in both directions. When a file doesn't map the same way in both directions, the file is ignored.

Example

Mappings that conflict and fail.

Joe has constructed a view as follows:

//depot/elm_proj/... //joe/elm/...
//depot/nowhere/* //joe/elm/doc/*

The depot file //depot/elm_proj/doc/help would map to //joe/elm/doc/help, but the same file in the client workspace would map back to the depot via the higher- precedence second line to //depot/nowhere/help. Because the file would be written back to a different location in the depot than where it was read from, Perforce doesn't map this name at all.

In older versions of Perforce, this was often used as a trick to exclude particular files from the client workspace. Because Perforce now has exclusionary mappings, this type of mapping is no longer useful, and should be avoided.

Referring to Files on Command Lines

File names provided as arguments to Perforce commands can be referred in one of two ways: by using the names of the files in the client workspace, or by providing the names of the files in the depot. When providing client workspace file names, the user may give the name in either local or Perforce syntax.

Local Syntax

Local syntax is simply a file's name as specified by the local shell or OS. This name may be an absolute path, or may be specified relative to the current directory, although it can only contain relative components at the beginning of the file name (i.e. it doesn't allow sub/dir/./here/foo.c). For example, on UNIX, Ed could refer to the README file at Elm's top level as /usr/edk/elm/README, or in a number of other ways.

Perforce Syntax

Perforce provides its own filename syntax which remains the same across operating systems. Filenames specified in this way begin with two slashes and the client or depot name, followed by the path name of the file relative to the client or depot root directory. The components of the path are separated by slashes.

Examples of Perforce syntax:


`//depot/...` `//elm_client/docs/help.1`

Reference

Multiple depots can be provided within a single perforce server. See chapter 16 for details.

Perforce syntax is sometimes called depot syntax or client syntax, depending on whether the file specifier refers to a file in the depot or on the client. But the syntax is the same in either case.

The specifier //... is occasionally used; it means `all files in all depots'.

Providing Files as Arguments to Commands

Because the client view provides a one-to-one mapping between any file in the client workspace and any file in the depot, any file can be specified within any Perforce command in client syntax, depot syntax, or local syntax. A depot's file specifier can be used to refer to a file in the client, and vice-versa. Perforce will do the necessary mapping to determine which file is actually used.

Any filenames provided to Perforce commands can be specified in any valid local syntax, or in Perforce syntax by depot or client. If a client filename is provided, Perforce uses the client view to locate the corresponding file in the depot. If a depot filename is given, the client view is used to locate the corresponding file in the client workspace.

Example

Uses of different syntaxes to refer to a file.

Ed wants to delete the src/lock.c file. He can give the p4 delete command in a number of ways:

· While in his client root directory, he could type

p4 delete src/lock.c

! Note !

The point of this section is worth repeating: any file can be specified within any Perforce command in client syntax, depot syntax, or local syntax. The examples in this manual will use these syntaxes interchangeably.

· While in the src subdirectory, he could type

p4 delete lock.c

· While in any directory on the client host, he can type

p4 delete //eds_elm/src/lock.c

p4 delete //depot/elm_proj/src/lock.c

p4 delete /usr/edk/elm/src/lock.c

Client names and depot names in a single Perforce server share the same namespace, so Perforce will never confuse a client name with a depot name. Client workspace names and depot names can never be the same.

Wildcards and Perforce Syntax

Perforce wildcards may be mixed with both local or Perforce syntax. For example:


Wildcard	Meaning
`J*`	Files in the current directory starting with `J`
`*/help`	All files called `help` in current subdirectories
`...`	All files under the current directory and its subdirectories
`.../*.c`	All such files ending in`.c`
`/usr/edk/...`	All files under `/usr/edk`
`//weasel/...`	All files on client `weasel`
`//depot/...`	All files in the depot

Name and String Limitations

File Names

Because of Perforce's naming conventions, certain characters cannot be used in file names. These include unprintable characters, the above wildcards, and the Perforce revision characters @ and #.

Name and Description Lengths

Label, branch, user, and client workspace names and descriptions no longer have any practical limit on their lengths.

Specifying Older File Revisions

All of the commands and examples we've seen thus far have been used to operate only on the most recent revisions of particular files, but many Perforce commands can act on older file versions. For example, if Ed types p4 sync //eds_elm/src/lock.c, the latest revision, or head revision, of lock.c is retrieved, but older revisions can be retrieved by tacking a revision specification onto the end of the file name. There are nine types of revision specifications:

! Warning !

Some OS shells will treat the # revision character as a comment character when it starts a new word. If your shell is one of these, escape the # before use.


Revision Specifier	Meaning	Examples
`file#n`	Revision number	`p4 sync lock.c#3` Refers to revision 3 of file `lock.c`
`file@n`	A changelist number¹	`p4 sync lock.c@126` Refers to the version of `lock.c` when changelist 126 was submitted, even if it was not part of the change. `p4 sync //depot/...@126` Refers to the state of the entire depot at changelist 126.
`file@label`	A label name²	`p4 sync lock.c@beta` The revision of `lock.c` in the label called `beta`
`file@clientname`	A client name. The revision of file last taken into client workspace clientname.	`p4 sync lock.c@lisag_ws` The revision of `lock.c` last taken into client workspace `lisag_ws`
`file#none`	The nonexistent revision.	`p4 sync lock.c#none` Says that there should be no version of l`ock.c` in the client workspace, even if one exists in the depot.
`file#head`	The head revision, or latest version, of the file.	`p4 sync lock.c#head` Except for explicitly noted exceptions, this is identical to referring to the file with no revision specifier.
`file#have`	The revision on the current client. This is synonymous to `@client` where client is the current client name.	`p4 sync lock.c#have` The revision of `lock.c` found in the current client.
`file@date`	The head revision of the file at 00:00:00 on the morning of that date. Dates are specified as `YYYY/MM/DD`.	`p4 sync lock.c@1998/05/18` The head revision of `lock.c` as of 00:00:00, May 18, 1998.
`file@"date time"`	The head revision of the file in the depot on the given date at the given time. The date is specified as above; the time is specified as `HH:MM:SS`.	`p4 sync lock.c@"1998/05/18 15:21:34"` The head revision of lock.c as of May 18, 1998, at 3:21:34 pm The date and the time must be separated by a single space, and the entire string should be quoted. The time is specified on the 24-hour clock. Warning: Perforce will accept two-digit years; these are assumed to fall in the twentieth century. For safety's sake, use two-digit years.

1. Changelist numbers are explained in chapter 7.
2. Chapter 8 discusses labels.

In all cases, if a file doesn't exist at the given revision number, it will appear as if the file doesn't exist at all. Thus, using a label to refer to a file that isn't in the label is indistinguishable from referring to a file that doesn't exist at all.

Using Revision Specifications without Filenames

Revision specifications can be provided without file names. This limits the command's action to the specified revision of all files in the depot or in the client's workspace. Thus, #head refers to the head revisions of all files in the depot, and @label refers to the revisions of all files in the named label.

Example

Retrieving files using revision specifiers.

Ed wants to retrieve all the doc files into his Elm doc subdirectory, but he wants to see only those revisions that existed at change number 30. He types

p4 sync //eds_elm/doc/*@30

Later, he creates another client for a different user. The new client should have all of the file revisions that Ed last synced. Ed sets up the new client specification and types

p4 sync //depot//elm_proj/...@eds_elm

He could have typed

p4 sync @eds_elm

and the effect would have been the same.

Another client needs all its files removed, but wants Perforce to know that it still contains those files. Ed sets P4CLIENT to the correct clientname, and types

p4 sync #none

Revision Ranges

A few Perforce client commands can limit their actions to a range of revision numbers, rather than just a single revision. A revision range is two revision specifications, separated by a comma. If only a single revision is given where a revision range is expected, the named revision specifies the end of the range, and the start of the range is assumed to be 1. If no revision number or range is given where a revision range is expected, the default is all revisions.

The commands that accept revision range specifications are:


`p4 changes`	`p4 file`	`p4 integrate`
`p4 jobs`	`p4 print`	`p4 sync`
`p4 verify`

File Types

Perforce supports normal text files as well as binary, "large text" files, keyword text files, Macintosh resource forks, and symbolic links. Perforce attempts to determine the type of the file automatically: when a file is opened with p4 add, Perforce first determines if the file is a regular file or a symbolic link, and then examines the first part of the file to determine whether is it text or binary. If any non-text characters are found, the file is assumed to be binary; otherwise, the file is assumed to be text.

The detected file type can be overridden with p4 add -t type; the file types and descriptions of these types are listed below.

Reference

RCS format and delta storage are described in detail at the start of the next chapter.

A file's type is inherited from one revision to the next. A file can be opened with a different type for the new revision with p4 edit -t type. If a file has already been opened with p4 add or p4 edit, its type can be changed with p4 reopen -t type.

Perforce must sometimes store the complete version of every file in the depot, but most often it stores only the changes in the file since the previous revision. This is called delta storage, and Perforce uses RCS format to store its deltas. The file's type determines whether full file or delta storage is used. When delta storage is used, file merges and file compares can be performed. Files that are stored in their full form can't be merged or compared.

Some of the file types are compressed to gzip format for storage in the depot. The compression occurs during the submission process, and decompression happens while syncing. The client workspace will always contain the file as it was submitted.

The Perforce file types are:

! Warning !

Do not try to fool Perforce into storing binary files in delta storage by changing the file type to text! If you add a file that that contains a ^Z as text from a Windows client, only the part of the file up to the ^Z will be stored in the depot.


Keyword	Description	Comments	Storage Type
`text`	Text file	Treated as text on the client.	`delta`
`xtext`	Executable text file	Like a `text` file, but execute permission is set on the client file.	`delta`
`ktext`	Text file with keyword expansion.	Any inclusion of the literal strings $Id$ or $Header$ within the file will be expanded to reflect the depot file name and revision number.	`delta`
`kxtext`	Executable text file with keyword expansion	Like a `ktext` file, but execute permission is set on the client file	`delta`
`binary`	Non-text file¹	Accessed as binary files on the client. Stored compressed within the depot.	`full file,compressed`
`xbinary`	Executable binary file	Like a `binary` file, but execute permission is set on the client file.	`full file,compressed`
`ctext`	Compressed text file	Like a `text` file, but stored compressed within the depot.	`full file,compressed`
`cxtext`	Executable compressed text file	Like an `xtext` file, but stored compressed within the depot.	`full file,compressed`
`symlink`	Symbolic link	UNIX clients access these as symbolic links; non-UNIX clients treat them as (small) `text` files.	`delta`
`resource`	Macintosh resource fork; stored compressed in the depot	Please see the Macintosh client release notes at the documentation section of the Perforce Web site.	`full file`
`ltext`	Long text file	Old file type; no longer needed; still supported. Use `ctext` instead.	`full file`
`xltext`	Executable long text file	Old file type; no longer needed; still supported. Use `cxtext` instead.	`full file`
`ubinary`	Uncompressed binary file	Straight `binary` files are compressed by Perforce; use `ubinary` when the file is already compressed, (e.g.,`.gif` files).	`full file`
`tempobj`	Temporary object²	Binary file; only the head revision is stored in the depot and the file is left writable in the client workspace. Useful for `.o` files.	`full file`
`tempxobj`	Temporary executable object	Executable binary file; only the head revision is stored in the depot and the file is left writable in the client workspace. Useful for executable files in which only the latest revision is needed by other users.	`full file`

1. In previous versions of Perforce, binary files were uncompressed. This corresponds to the perforce 98.2 ubinary format, and files stored as binary in previous versions will now have a file type of ubinary. To compress these files, use p4 reopen -t binary files. Binary files that are already compressed, such as .gif files, need not be compressed again.

2. When syncing old revisions of tempobj or tempxobj files into the client workspace, the head revision, which is the only revision, will be the revision that is synced.

To find the type of an existing file, use the p4 opened reporting command.

Forms and Perforce Commands

Certain Perforce commands, such as p4 client and p4 submit, present a form to the user to be filled in with values. This form is displayed in the editor defined in the environment variable EDITOR. When the user changes the form and exits the editor, the form is parsed by Perforce, checked for errors, and used to complete the command operation. If there are errors, Perforce gives an error message and you must try again.

The rules of form syntax are simple: keywords must be against the left margin and end with a colon, and values must either be on the same line as the keyword or indented on the lines beneath the keyword. Only the keywords already present on the form are recognized. Some keywords, such as the Client: field in the p4 client form, take a single value; other fields, such as Description: , take a block of text; and others, like View: , take a list of lines.

Certain fields, like Client: in p4 client, can't have their values changed; others, like Description: in p4 submit, must have their values changed. If you don't change a field that needs to be changed, or vice-versa, the worst that will happen is that you'll get an error. We've done our best to make these cases as self-evident as possible; when in doubt, use p4 help command.

General Reporting Commands

Many reporting commands have specialized functions, and these are discussed in later chapters. The following reporting commands give the most generally useful information; all these commands can take file name arguments, with or without wildcards, to limit reporting to specific files. Without the file arguments, the reports are generated for all files.

These reports always generate information on depot files, not files within the client workspace. As with any other Perforce command, when a client file is provided on the command line, Perforce maps it to the proper depot file.


Command	Meaning
`p4 filelog`	Generates a report on each revision of the file(s), in reverse chronological order.
`p4 files`	Lists file name, latest revision number, file type, and other information about the named file(s).
`p4 sync -n`	Tells you what `p4 sync` would do, without doing it.
`p4 have`	Lists all the revisions of the named files within the client that were last gotten from the depot. Without any files specifier, it lists all the files in the depot that the client has.
`p4 opened`	Reports on all files in the depot that are currently open for edit, add, delete, branch, or integrate within the client workspace.
`p4 print`	Lists the contents of the named file(s) to standard output.
`p4 where`	Given a file argument, display the mapping of that file within the depot, the client workspace, and the local OS.

Revision specifiers can be used with all of these reporting commands, for example

p4 files @clientname

can be used to report on all the files in the depot that are currently found in client clientname.

Chapter 12, the reporting chapter, contains a more detailed discussion of each of these commands.

Perforce 98.2 p4 User's Guide


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