tramp supports starting new running processes on the remote host for discovering remote file names. Emacs packages on the remote host need no specific modifications for tramp's use.
This type of integration does not work with the ftp method,
and does not support the pty association as specified in
start-file-process work on the remote
host when the variable
default-directory is remote:
(let ((default-directory "/ssh:remote.host:")) (start-file-process "grep" (get-buffer-create "*grep*") "/bin/sh" "-c" "grep -e tramp *"))
Remote processes do not apply to GVFS (see GVFS based methods)
because the remote file system is mounted on the local host and
tramp just accesses by changing the
tramp starts a remote process when a command is executed in a
remote file or directory buffer. As of now, these packages have been
integrated to work with tramp: compile.el (commands
grep) and gud.el (
For tramp to find the command on the remote, it must be
accessible through the default search path as setup by tramp
upon first connection. Alternatively, use an absolute path or extend
tramp-remote-path (see Remote programs):
(add-to-list 'tramp-remote-path "~/bin") (add-to-list 'tramp-remote-path "/appli/pub/bin")
tramp-remote-process-environment to suit the remote
program's environment for the remote host.
tramp-remote-process-environment is a list of strings
structured similar to
process-environment, where each element
is a string of the form ‘ENVVARNAME=VALUE’.
To avoid any conflicts with local host variables set through local configuration files, such as ~/.profile, use ‘ENVVARNAME=’ to unset them for the remote environment.
add-to-list to add entries:
(add-to-list 'tramp-remote-process-environment "JAVA_HOME=/opt/java")
Modifying or deleting already existing values in the
tramp-remote-process-environment list may not be feasible on
restricted remote hosts. For example, some system administrators
disallow changing HISTORY variable. To accommodate such
restrictions when using tramp, fix the
tramp-remote-process-environment by the following code in the
local .emacs file:
(let ((process-environment tramp-remote-process-environment)) (setenv "HISTORY" nil) (setq tramp-remote-process-environment process-environment))
tramp does not use the defaults specified in
process-environment for running
start-file-process on remote hosts. When values from
process-environment are needed for remote processes, then set
them as follows:
(let ((process-environment (cons "HGPLAIN=1" process-environment))) (process-file ...))
This works only for environment variables not already set in the
For integrating other Emacs packages so tramp can execute remotely, please file a bug report. See Bug Reports.
To allow a remote program to create an X11 window on the local host, set the DISPLAY environment variable for the remote host as follows in the local .emacs file:
(add-to-list 'tramp-remote-process-environment (format "DISPLAY=%s" (getenv "DISPLAY")))
(getenv "DISPLAY") should return a recognizable name for the
local host that the remote host can redirect X11 window
interactions. If querying for a recognizable name is not possible for
whatever reason, then replace
(getenv "DISPLAY") with a
hard-coded, fixed name. Note that using
:0 for X11 display name
here will not work as expected.
An alternate approach is specify
ForwardX11 yes or
ForwardX11Trusted yes in the file ~/.ssh/config on the
shellon a remote host
Set explicit-shell-file-name to the appropriate shell name when using tramp between two hosts with different operating systems, such as ‘windows-nt’ and ‘gnu/linux’. This option ensures the correct name of the remote shell program.
Starting with Emacs 24, when explicit-shell-file-name is
shell interactively will prompt
for a shell name.
shell-commandon a remote host
shell-command executes commands synchronously or asynchronously
on remote hosts and displays output in buffers on the local
C-x C-f /sudo:: <RET> M-! tail -f /var/log/syslog.log & <RET>
tail command outputs continuously to the local buffer, *Async Shell Command*
M-x auto-revert-tail-mode runs similarly showing continuous output.
eshellon a remote host
tramp is integrated into eshell.el, which enables
interactive eshell sessions on remote hosts at the command prompt.
You must add the module
eshell-modules-list. Here's a sample interaction after opening
M-x eshell on a remote host:
~ $ cd /sudo::/etc <RET> /sudo:root@host:/etc $ hostname <RET> host /sudo:root@host:/etc $ id <RET> uid=0(root) gid=0(root) groups=0(root) /sudo:root@host:/etc $ find-file shadow <RET> #<buffer shadow> /sudo:root@host:/etc $
eshell in Emacs 23.2 added custom
sudo commands that set the default directory correctly for the
*eshell* buffer. tramp silently updates
tramp-default-proxies-alist with an entry for this directory
~ $ cd /ssh:user@remotehost:/etc <RET> /ssh:user@remotehost:/etc $ find-file shadow <RET> File is not readable: /ssh:user@remotehost:/etc/shadow /ssh:user@remotehost:/etc $ sudo find-file shadow <RET> #<buffer shadow> /ssh:user@remotehost:/etc $ su - <RET> /su:root@remotehost:/root $ id <RET> uid=0(root) gid=0(root) groups=0(root) /su:root@remotehost:/root $
gud.el provides a unified interface to symbolic debuggers
tramp can run debug on remote hosts by calling
with a remote file name:
M-x gdb <RET> Run gdb (like this): gdb --annotate=3 /ssh:host:~/myprog <RET>
Relative file names are based on the remote default directory. When myprog.pl exists in /ssh:host:/home/user, valid calls include:
M-x perldb <RET> Run perldb (like this): perl -d myprog.pl <RET>
Just the local part of a remote file name, such as perl -d /home/user/myprog.pl, is not possible.
Arguments of the program to be debugged must be literal, can take relative or absolute paths, but not remote paths.
winexe runs processes on a remote Windows host, and
tramp can use it for
tramp-smb-winexe-program specifies the local winexe
command. Powershell V2.0 on the remote host is required to run
processes triggered from tramp.
explicit-shell-file-name and explicit-*-args have to be set properly so M-x shell can open a proper remote shell on a Windows host. To open cmd, set it as follows:
(setq explicit-shell-file-name "cmd" explicit-cmd-args '("/q"))
To open powershell as a remote shell, use this:
(setq explicit-shell-file-name "powershell" explicit-powershell-args '("-file" "-"))