SSH – Sourcing BASH_ENV for non-interactive SSH commands

sshsshd

I'm hoping to get the $BASH_ENV var to source for non-interactive ssh commands.

I do see my BASH_ENV:

ssh server.example.com env | grep BASH
BASH_ENV=/tmp/set_bash_env_profile

If I do simple ssh login, and env | wc -l I get 85, thanks to $BASH_ENV env var, but if:

ssh server.example.com env | wc -l
17

I get just 17…

I tried ForceCommand in the sshd_config as described here but in my case, the SSH_ORIGINAL_COMMAND is not being set.

Best Answer

Presumably you're setting BASH_ENV in your .bashrc. Bash loads .bashrc when it's interactive and not a login shell, or when it's a login shell that's invoked by rshd or (in many distributions, but it's a compile-time option) sshd. That's too late for this instance of bash. Put the commands directly in ~/.bashrc.

# .bashrc
if [[ $- = *i* ]]; then
  # Commands for interactive use: prompt, aliases, key bindings, etc.
  # Don't set environment variables here, that goes in .profile.
else
  # Commands executed only on remote logins.
  # You can set environment variables here. Do not output anything.
fi

If you only need to set environment variables, you can use ~/.pam_environment instead, which is used for any kind of login. See What's the best distro/shell-agnostic way to set environment variables?

For other ways to execute commands when logging in non-interactively over SSH, see sh startup files over ssh

Related Solutions

Bash – Can ‘ssh ‘ be configured to always load server-side startup files

Create a wrapper shell function sshc which prefixes the source ~/.bash_profile boiler plate for you:

function sshc {
    local host=$1
    local cmd=$2

    ssh $host "source ~/.bash_profile && $cmd"
}

You can then use this as:

$ sshc localhost 'which perl'
/home/calid/perl5/perlbrew/perls/perl-5.20.1/bin/perl

Bash – Run a command in an interactive shell with ssh after sourcing .bashrc

The problem is that you are trying to run an alias in a non-interactive shell. When you run ssh user@computer command, command is run non-interactively.

Non interactive shells don't read aliases (from man bash):

Aliases are not expanded when the shell is not interactive, unless the expand_aliases shell option is set using shopt (see the description of shopt under SHELL BUILTIN COMMANDS below).

It works if you run it again manually because the final bash command starts an interactive shell so your aliases are now available.

As an alternative, you could launch an interactive shell (bash -i) instead of a simple login shell (bash -l) on the remote machine to run your alias:

ssh user@remote_computer -t 'bash -ic "my_alias;bash"'

This seems a very complicated approach though. You haven't explained why exactly you need to do this but consider these alternatives:

Just start a normal login interactive shell on the remote machine and run the command manually:
```
user@local $ ssh user@remote
user@remote $ my_alias
```
If you always want that alias to be run when you connect to this computer, edit the ~/.profile (or ~/.bash_profile, if present) of the remote computer and add this line at the end:
```
my_alias
```
Because ~/.profile is read each time a login shell is started (so, each time you connect via ssh, for example), that will cause my_alias to be run each time you connect.

Note that by default, login shells read ~/.profile or ~/.bash_profile and ignore ~/.bashrc. Some distributions (Debian and its derivatives and Arch, for example) distributions like Ubuntu have their default ~/.profile or ~/.bash_profile files source ~/.bashrc which means that your aliases defined in ~/.bashrc will also be available in a login shell. This isn't true for all distributions, so you might have to edit your ~/.profile manually to have it source ~/.bashrc. Also note that if ~/.bash_profile exists, ~/.profile will be ignored by bash.

Best Answer

Related Solutions

Bash – Can ‘ssh ‘ be configured to always load server-side startup files

Bash – Run a command in an interactive shell with ssh after sourcing .bashrc

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