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* tramp.texi (Version Control): Remove.
(Obtaining Tramp): Update cvs checkout command. Remove nightly tarballs reference. (External methods): Correct `scpc' concept index entries. New method `rsyncc'. (External packages): New subsections "Filename completion" and "File attributes cache".
This commit is contained in:
Michael Albinus
parent
e7adeadcd3
commit
b59329e062
@ -1,3 +1,13 @@
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2009-08-28 Michael Albinus <michael.albinus@gmx.de>
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* tramp.texi (Version Control): Remove.
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(Obtaining Tramp): Update cvs checkout command. Remove nightly tarballs
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reference.
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(External methods): Correct `scpc' concept index entries. New method
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`rsyncc'.
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(External packages): New subsections "Filename completion" and "File
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attributes cache".
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2009-08-27 Jay Belanger <jay.p.belanger@gmail.com>
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* calc.texi (Rewrite Rules): Improve the example.
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@ -157,7 +157,6 @@ For the end user:
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For the developer:
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* Version Control:: The inner workings of remote version control.
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* Files directories and localnames:: How file names, directories and localnames are mangled and managed.
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* Traces and Profiles:: How to Customize Traces.
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* Issues:: Debatable Issues and What Was Decided.
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@ -208,19 +207,6 @@ Using @value{tramp}
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* Remote processes:: Integration with other @value{emacsname} packages.
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* Cleanup remote connections:: Cleanup remote connections.
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The inner workings of remote version control
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* Version Controlled Files:: Determining if a file is under version control.
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* Remote Commands:: Executing the version control commands on the remote machine.
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* Changed workfiles:: Detecting if the working file has changed.
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* Checking out files:: Bringing the workfile out of the repository.
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* Miscellaneous Version Control:: Things related to Version Control that don't fit elsewhere.
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Things related to Version Control that don't fit elsewhere
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* Remote File Ownership:: How VC determines who owns a workfile.
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* Back-end Versions:: How VC determines what release your RCS is.
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How file names, directories and localnames are mangled and managed
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* Localname deconstruction:: Breaking a localname into its components.
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@ -416,7 +402,7 @@ Or follow the example session below:
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@example
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] @strong{cd ~/@value{emacsdir}}
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] @strong{export CVS_RSH="ssh"}
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] @strong{cvs -z3 -d:ext:anoncvs@@savannah.gnu.org:/cvsroot/tramp co tramp}
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] @strong{cvs -z3 -d:pserver:anonymous@@cvs.savannah.gnu.org:/sources/tramp co tramp}
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@end example
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@noindent
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@ -440,11 +426,6 @@ script:
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] @strong{autoconf}
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@end example
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People who have no direct CVS access (maybe because sitting behind a
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blocking firewall), can try the
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@uref{http://savannah.gnu.org/cvs-backup/tramp-sources.tar.gz, Nightly
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CVS Tree Tarball} instead of.
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@node History
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@chapter History of @value{tramp}
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@ -896,10 +877,10 @@ This method supports the @samp{-p} argument.
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@item @option{scpc} --- @command{ssh} and @command{scp}
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@cindex method scpx
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@cindex scpx method
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@cindex scp (with scpx method)
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@cindex ssh (with scpx method)
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@cindex method scpc
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@cindex scpc method
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@cindex scp (with scpc method)
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@cindex ssh (with scpc method)
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Newer versions of @option{ssh} (for example OpenSSH 4) offer an option
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@option{ControlMaster}. This allows @option{scp} to reuse an existing
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@ -915,6 +896,20 @@ ssh localhost -o ControlMaster=yes
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This method supports the @samp{-p} argument.
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@item @option{rsyncc} --- @command{ssh} and @command{rsync}
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@cindex method rsyncc
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@cindex rsyncc method
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@cindex rsync (with rsyncc method)
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@cindex ssh (with rsyncc method)
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Like the @option{scpc} method, @option{rsyncc} improves the underlying
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@command{ssh} connection by the option @option{ControlMaster}. This
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allows @command{rsync} to reuse an existing @command{ssh} channel,
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which increases performance.
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This method supports the @samp{-p} argument.
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@item @option{pscp} --- @command{plink} and @command{pscp}
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@cindex method pscp
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@cindex pscp method
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@ -2302,7 +2297,8 @@ Filename completion works with @value{tramp} for completion of method
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names, of user names and of machine names as well as for completion of
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file names on remote machines.
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@ifset emacs
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In order to enable this, Partial Completion mode must be set on.
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In order to enable this, partial completion must be activated in your
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@file{.emacs}.
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@ifinfo
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@xref{Completion Options, , , @value{emacsdir}}.
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@end ifinfo
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@ -3257,153 +3253,6 @@ This resets also the @value{ftppackagename} plugins.
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@c For the developer
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@node Version Control
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@chapter The inner workings of remote version control
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@cindex Version Control
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Unlike @value{ftppackagename}, @value{tramp} has full shell access to the
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remote machine. This makes it possible to provide version control for
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files accessed under @value{tramp}.
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The actual version control binaries must be installed on the remote
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machine, accessible in the directories specified in
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@code{tramp-remote-path}.
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This transparent integration with the version control systems is one of
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the most valuable features provided by @value{tramp}, but it is far from perfect.
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Work is ongoing to improve the transparency of the system.
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@menu
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* Version Controlled Files:: Determining if a file is under version control.
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* Remote Commands:: Executing the version control commands on the remote machine.
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* Changed workfiles:: Detecting if the working file has changed.
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* Checking out files:: Bringing the workfile out of the repository.
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* Miscellaneous Version Control:: Things related to Version Control that don't fit elsewhere.
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@end menu
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@node Version Controlled Files
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@section Determining if a file is under version control
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The VC package uses the existence of on-disk revision control master
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files to determine if a given file is under revision control. These file
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tests happen on the remote machine through the standard @value{tramp} mechanisms.
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@node Remote Commands
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@section Executing the version control commands on the remote machine
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There are no hooks provided by VC to allow intercepting of the version
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control command execution. The calls occur through the
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@code{call-process} mechanism, a function that is somewhat more
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efficient than the @code{shell-command} function but that does not
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provide hooks for remote execution of commands.
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To work around this, the functions @code{vc-do-command} and
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@code{vc-simple-command} have been advised to intercept requests for
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operations on files accessed via @value{tramp}.
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In the case of a remote file, the @code{shell-command} interface is
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used, with some wrapper code, to provide the same functionality on the
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remote machine as would be seen on the local machine.
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@node Changed workfiles
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@section Detecting if the working file has changed
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As there is currently no way to get access to the mtime of a file on a
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remote machine in a portable way, the @code{vc-workfile-unchanged-p}
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function is advised to call an @value{tramp} specific function for remote files.
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The @code{tramp-vc-workfile-unchanged-p} function uses the functioning VC
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diff functionality to determine if any changes have occurred between the
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workfile and the version control master.
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This requires that a shell command be executed remotely, a process that
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is notably heavier-weight than the mtime comparison used for local
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files. Unfortunately, unless a portable solution to the issue is found,
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this will remain the cost of remote version control.
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@node Checking out files
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@section Bringing the workfile out of the repository
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VC will, by default, check for remote files and refuse to act on them
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when checking out files from the repository. To work around this
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problem, the function @code{vc-checkout} knows about @value{tramp} files and
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allows version control to occur.
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@node Miscellaneous Version Control
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@section Things related to Version Control that don't fit elsewhere
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Minor implementation details, &c.
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@menu
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* Remote File Ownership:: How VC determines who owns a workfile.
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* Back-end Versions:: How VC determines what release your RCS is.
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@end menu
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@node Remote File Ownership
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@subsection How VC determines who owns a workfile
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@value{emacsname} provides the @code{user-login-name} function to
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return the login name of the current user as well as mapping from
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arbitrary user id values back to login names. The VC code uses this
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functionality to map from the uid of the owner of a workfile to the
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login name in some circumstances.
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This will not, for obvious reasons, work if the remote system has a
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different set of logins. As such, it is necessary to delegate to the
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remote machine the job of determining the login name associated with a
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uid.
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Unfortunately, with the profusion of distributed management systems such
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as @code{NIS}, @code{NIS+} and @code{NetInfo}, there is no simple,
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reliable and portable method for performing this mapping.
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Thankfully, the only place in the VC code that depends on the mapping of
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a uid to a login name is the @code{vc-file-owner} function. This returns
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the login of the owner of the file as a string.
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This function has been advised to use the output of @command{ls} on the
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remote machine to determine the login name, delegating the problem of
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mapping the uid to the login to the remote system which should know more
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about it than I do.
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@node Back-end Versions
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@subsection How VC determines what release your RCS is
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VC needs to know what release your revision control binaries you are
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running as not all features VC supports are available with older
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versions of @command{rcs(1)}, @command{cvs(1)} or @command{sccs(1)}.
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The default implementation of VC determines this value the first time it
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is needed and then stores the value globally to avoid the overhead of
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executing a process and parsing its output each time the information is
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needed.
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Unfortunately, life is not quite so easy when remote version control
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comes into the picture. Each remote machine may have a different version
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of the version control tools and, while this is painful, we need to
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ensure that unavailable features are not used remotely.
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To resolve this issue, @value{tramp} currently takes the sledgehammer
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approach of making the release values of the revision control tools
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local to each @value{tramp} buffer, forcing VC to determine these values
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again each time a new file is visited.
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This has, quite obviously, some performance implications. Thankfully,
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most of the common operations performed by VC do not actually require
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that the remote version be known. This makes the problem far less
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apparent.
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Eventually these values will be captured by @value{tramp} on a system by
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system basis and the results cached to improve performance.
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@node Files directories and localnames
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@chapter How file names, directories and localnames are mangled and managed.
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@ -3434,6 +3283,7 @@ effect while preserving the @value{tramp} file name information.
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@ifset emacs
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@node External packages
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@section Integration with external Lisp packages.
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@subsection Filename completion.
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While reading filenames in the minibuffer, @value{tramp} must decide
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whether it completes possible incomplete filenames, or not. Imagine
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@ -3449,12 +3299,31 @@ remote host @option{ssh}.
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External packages, which use other characters for completing filenames
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in the minibuffer, must signal this to @value{tramp}. For this case,
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the variable @code{tramp-completion-mode} can be bound temporarily to
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a non-nil value.
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a non-@code{nil} value.
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@lisp
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(let ((tramp-completion-mode t))
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...)
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@end lisp
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@subsection File attributes cache.
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When @value{tramp} runs remote processes, files on the remote host
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could change their attributes. Consequently, @value{tramp} must flush
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its complete cache keeping attributes for all files of the remote host
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it has seen so far.
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This is a performance degradation, because the lost file attributes
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must be recomputed, when needed again. In cases the caller of
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@code{process-file} knows that there are file attribute changes, it
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shall let-bind the variable @code{process-file-side-effects} to
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@code{nil}. @value{tramp} wouldn't flush the file attributes cache then.
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@lisp
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(let (process-file-side-effects)
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...)
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@end lisp
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@end ifset
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