NAME
aegis clone - make an exact copy of a change
SYNOPSIS
aegis -CLone [ option... ] change-number [ change-number ]
aegis -CLone -Help
aegis -CLone -VERSion
DESCRIPTION
The aegis -CLone command is used to create exact replicas of changes.
This is of most use when a change need to be applied to several
parallel branches.
One change number must be supplied. This is the change to be
replicated. If any branch options are given (see below) the mandatory
change number applies to the branch specified. If no branch is
specified, the change applies to the project (implicit or explicit).
If the optional second change number is supplied, this is the change
number to be created to hold the replica; if it is not supplied, the
next available change number will be used.
If the change to be replicated has been completed, the appropriate file
revisions will be extracted from history; otherwise the files will be
copied from the development directory of the change to be copied. Be
warned: if a file in the change which was cloned subsequently changes,
those changes will not automagically be tracked. It is best if changes
are cloned at a stable time, such as one of the states after develop
end, or even after integrate pass.
Development Directory Location
Please Note: Aegis also consults the underlying file system, to
determine its notion of maximum file size. Where the file system’s
maximum file size is less than maximum_filename_length, the filesystem
wins. This can happen, for example, when you are using the Linux
UMSDOS file system, or when you have an NFS mounted an ancient V7
filesystem. Setting maximum_filename_length to 255 in these cases does
not alter the fact that the underlying file systems limits are far
smaller (12 and 14, respectively).
If your development directories (or your whole project) is on
filesystems with filename limitations, or a portion of the
heterogeneous builds take place in such an environment, it helps to
tell Aegis what they are (using the project config file’s fields) so
that you don’t run into the situation where the project builds on the
more permissive environments, but fails with mysterious errors in the
more limited environments.
If your development directories are routinely on a Linux UMSDOS
filesystem, you would probably be better off setting
dos_filename_required = true, and also changing the
development_directory_template field. Heterogeneous development with
various Windows environments may also require this.
WHITEOUT
Aegis provides you with what is often called a “view path” which
indicates to development tools (compilers, build systems, etc) look
first in the development directory, then in the branch baseline, and so
on up to the trunk baseline.
The problem with view paths is that in order to remove files, you need
some kind of "whiteout" to say “stop looking, it’s been removed.”
When you user the aerm(1) or aemv(1) commands, this means "add
information to this change which will remove the file from the baseline
when this change is integrated". I.e. while the change is in the being
developed state, the file is only "removed" in the development
directory - it’s still present in the baseline, and will be until the
change is successfully integrated.
When you use the aerm(1) or aemv(1) commands, Aegis will create a 1K
file to act as the whiteout. It’s contents are rather ugly so that if
you compile or include the "removed" file accidentally, you get a fatal
error. This will remind you to remove obsolete references.
When the change in integrated, the removed file is not copied/linked
from the baseline to the integration directory, and is not copied from
the development directory. At this time it is physically gone (no
whiteout). It is assumed that because of the error inducing whiteout
all old references were found and fixed while the change was in the
being developed state.
File Manifests
When generating list of files to be compiled or linked, it is important
that the file manifest be generated from information known by Aegis,
rather than from the file system. This is for several reasons:
(a) Aegis knows exactly what (source) files are where, whereas
everything else is inferring Aegis’ knowledge; and
(b) looking in the file system is hard when the view path is longer
that 2 directories (and Aegis’ branching method can make it
arbitrarily long); and
(c) The whiteout files, and anything else left “lying around”, will
confuse any method which interrogates the file system.
The easiest way to use Aegis’ file knowledge is with something like an
awk(1) script processing the Aegis file lists. For example, you can do
this with make(1) as follows:
# generate the file manifest
manifest.make.inc: manifest.make.awk
( aegis -l cf -ter ; aegis -l pf -ter ) | \
awk -f manifest.make.awk > manifest.make.inc
# now include the file manifest
include manifest.make.inc
Note: this would be inefficient of you did it once per directory, but
there is nothing stopping you writing numerous assignments into the
manifest.make.inc file, all in one pass.
It is possible to do the same thing with Aegis’ report generator (see
aer(1) for more information), but this is more involved than the awk(1)
script. However, with the information "straight from the horse’s
mouth" as it were, it can also be much smarter.
This file manifest would become out-of-date without an interlock to
Aegis’ file operations commands. By using the project-file_command and
change_file_command fields of the project config file (see aepconf(5)
for more information), you can delete this file at strategic times.
/* run when the change file manifest is altered */
change_file_command = "rm -f manifest.make.inc";
/* run when the project file manifest is altered */
project_file_command = "rm -f manifest.make.inc";
The new file manifest will thus be re-built during the next aeb(1)
command.
Options and Preferences
There is a -No-WhiteOut option, which may be used to suppress whiteout
files when you use the aerm(1) and aemv(1) commands. There is a
corresponding -WhiteOut option, which is usually the default.
There is a whiteout_preference field in the user preferences file (see
aeuconf(5) for more information) if you want to set this option more
permanently.
Whiteout File Templates
The whiteout_template field of the project config file may be used to
produce language-specific error files. If no whiteout template entry
matches, a very ugly 1KB file will be produced - it should induce
compiler errors for just about any language.
If you want a more human-readable error message, entries such as
whiteout_template =
[
{
pattern = [ "*.[ch]" ];
body = "#error This file has been removed.";
}
];
can be very effective (this example assumes gcc(1) is being used).
If it is essential that no whiteout file be produced, say for C source
files, you could use a whiteout template such as
whiteout_template =
[
{ pattern = [ "*.c" ]; }
];
because an absent body sub-field means generate no whiteout file at
all.
You may have more than one whiteout template entry, but note that the
order of the entries is important. The first entry which matches will
be used.
Notification
The notification commands that would be run by the aecp(1), aedb(1),
aenf(1), aent(1) and aerm(1) commands are run, as appropriate. The
project_file_command is also run, if set. See aepconf(5) for more
information.
Cloning and Merging
When you use aeclone(1) to clone a change set, and then integrate one
of the two change sets, you will observe that Aegis says that the files
of the un-integrated change are now out-of-date.
If you run aem(1) to bring the out-of-date files back up-to-date,
fmerge(1) and some (but not) all other merging tools, it signals just
about everything as a conflict, even though both alternatives are
identical.
The problem is that two changes making identical edits to the same
place in the same file are a logical conflict, even if not an actual
conflict, and it takes a human to figure out the difference. Think of
a shopping list: the ensuite needs more soap, and so does the main
bathroom. The second "soap" on the merge of the two shopping lists
isn’t a duplicate, you really do need two boxes of soap. Sometimes
edits of source files are the same: sometimes the logical conflict is
resolved by applying both identical edits, not just one.
This is just the fmerge(1) command being more conservative than RCS’s
merge(1) command.
The easiest way to deal with this common situation it to run an
aecpu -unchanged
command before you run the aem(1) merge command, and you will have less
grief. It’s also worth remembering that Aegis stashes the original
file with a ,B suffix (B for backup) so you can simply
mv fubar,B fubar
if you know that all of the conflicts are logical conflicts.
OPTIONS
The following options are understood:
-BRanch number
This option may be used to specify a different branch for the
origin file, rather than the baseline. (See also -TRunk
option. Please Note: the -BRanch option does not take a
project name, just the branch number suffix.
-GrandParent
This option may be used to specify the grandparent branch (one
up from the current branch) for the origin file, rather than
the baseline. (The -grandparent option is the same as the
“-branch ..” option.)
-Change number
This option may be used to specify a particular change within a
project. See aegis(1) for a complete description of this
option.
-DIRectory path
This option may be used to specify which directory is to be
used. It is an error if the current user does not have
appropriate permissions to create the directory path given.
This must be an absolute path.
Caution: If you are using an automounter do not use ‘pwd‘ to
make an absolute path, it usually gives the wrong answer.
-Help
This option may be used to obtain more information about how to
use the aegis program.
-List
This option may be used to obtain a list of suitable subjects
for this command. The list may be more general than expected.
-WhiteOut
This option may be used to request that deleted files be
replaced by a “whiteout” file in the development directory.
The idea is that compiling such a file will result in a fatal
error, in order that all references may be found. This is
usually the default.
-No_WhiteOut
This option may be used to request that no “whiteout” file be
placed in the development directory.
-Output filename
This option may be used to specify a filename which is to be
written with the automatically determined change number.
Useful for writing scripts.
-Project name
This option may be used to select the project of interest.
When no -Project option is specified, the AEGIS_PROJECT
environment variable is consulted. If that does not exist, the
user’s $HOME/.aegisrc file is examined for a default project
field (see aeuconf(5) for more information). If that does not
exist, when the user is only working on changes within a single
project, the project name defaults to that project. Otherwise,
it is an error.
-TRunk
This option may be used to specify the project trunk for the
origin file, rather than the baseline. (See also -BRanch
option, the -trunk option is the same as the “-branch -”
option.)
-Wait This option may be used to require Aegis commands to wait for
access locks, if they cannot be obtained immediately. Defaults
to the user’s lock_wait_preference if not specified, see
aeuconf(5) for more information.
-No_Wait
This option may be used to require Aegis commands to emit a
fatal error if access locks cannot be obtained immediately.
Defaults to the user’s lock_wait_preference if not specified,
see aeuconf(5) for more information.
See also aegis(1) for options common to all aegis commands.
All options may be abbreviated; the abbreviation is documented as the
upper case letters, all lower case letters and underscores (_) are
optional. You must use consecutive sequences of optional letters.
All options are case insensitive, you may type them in upper case or
lower case or a combination of both, case is not important.
For example: the arguments "-project, "-PROJ" and "-p" are all
interpreted to mean the -Project option. The argument "-prj" will not
be understood, because consecutive optional characters were not
supplied.
Options and other command line arguments may be mixed arbitrarily on
the command line, after the function selectors.
The GNU long option names are understood. Since all option names for
aegis are long, this means ignoring the extra leading ’-’. The
"--option=value" convention is also understood.
ERRORS
It is an error if the current user is not an administrator of the
project. (In some cases it is possible for developers of a project to
create changes, see aepattr(5) for more information.)
EXIT STATUS
The aegis command will exit with a status of 1 on any error. The aegis
command will only exit with a status of 0 if there are no errors.
ENVIRONMENT VARIABLES
See aegis(1) for a list of environment variables which may affect this
command. See aepconf(5) for the project configuration file’s project_
specific field for how to set environment variables for all commands
executed by Aegis.
SEE ALSO
aenc(1) Create a new change.
aeca(1) modify the attributes of a change
aena(1) add a new administrator to a project
aepa(1) modify the attributes of a project
COPYRIGHT
aegis version 4.24.3.D001
Copyright (C) 1991, 1992, 1993, 1994, 1995, 1996, 1997, 1998, 1999,
2000, 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009, 2010 Peter
Miller
The aegis program comes with ABSOLUTELY NO WARRANTY; for details use
the ’aegis -VERSion License’ command. This is free software and you
are welcome to redistribute it under certain conditions; for details
use the ’aegis -VERSion License’ command.
AUTHOR
Peter Miller E-Mail: millerp@canb.auug.org.au
/\/\* WWW: http://www.canb.auug.org.au/~millerp/