Support $ENV in Tramp

* doc/misc/tramp.texi (Remote processes): Explain setting $ENV.

* etc/NEWS: Explain the "ENV" environment variable in
`tramp-remote-process-environment'.

* lisp/net/tramp-sh.el (tramp-remote-process-environment): Add "ENV=''".
(tramp-open-shell): Read $ENV value from
`tramp-remote-process-environment'.
(tramp-open-connection-setup-interactive-shell): Set values in
proper order.

1 files changed, 15 insertions, 5 deletions

diff --git a/doc/misc/tramp.texi b/doc/misc/tramp.texi
index 2c41dddd1b..37518284bb 100644
--- a/doc/misc/tramp.texi
+++ b/doc/misc/tramp.texi
@@ -2369,9 +2369,9 @@ program's environment for the remote host.
 structured similar to @code{process-environment}, where each element
 is a string of the form @samp{ENVVARNAME=VALUE}.
 
-To avoid any conflicts with local host variables set through local
-configuration files, such as @file{~/.profile}, use @samp{ENVVARNAME=}
-to unset them for the remote environment.
+To avoid any conflicts with local host environment variables set
+through local configuration files, such as @file{~/.profile}, use
+@samp{ENVVARNAME=} to unset them for the remote environment.
 
 @noindent
 Use @code{add-to-list} to add entries:
@@ -2383,8 +2383,8 @@ Use @code{add-to-list} to add entries:
 Modifying or deleting already existing values in the
 @code{tramp-remote-process-environment} list may not be feasible on
 restricted remote hosts.  For example, some system administrators
-disallow changing @env{HISTORY} variable.  To accommodate such
-restrictions when using @value{tramp}, fix the
+disallow changing @env{HISTORY} environment variable.  To accommodate
+such restrictions when using @value{tramp}, fix the
 @code{tramp-remote-process-environment} by the following code in the
 local @file{.emacs} file:
 
@@ -2394,6 +2394,16 @@ local @file{.emacs} file:
   (setq tramp-remote-process-environment process-environment))
 @end lisp
 
+Setting the @env{ENV} environment variable instructs some shells to
+read an initialization file.  Per default, @value{tramp} has disabled
+this.  You could overwrite this behaviour by evaluating
+
+@lisp
+(let ((process-environment tramp-remote-process-environment))
+  (setenv "ENV" "$HOME/.profile")
+  (setq tramp-remote-process-environment process-environment))
+@end lisp
+
 @value{tramp} does not use the defaults specified in
 @code{process-environment} for running @code{process-file} or
 @code{start-file-process} on remote hosts.  When values from