24

My problem is that I need to set a few variables, and output a few lines every time I login to the ssh shell, and at the same time I have to be able to use sftp to tarnsfer files via Filezilla.

Now, as per the openssh FAQ at http://www.openssh.org/faq.html, if your startup scripts echo any kind of output, it messes up with sftp. So it either delays indefinitely, or errors out with a "Connection closed by server with exit code 128".

I have tried solutions like moving .bashrc to .bash_profile, or using the following code in .bashrc:

if [ "$TERM" != "dumb" ]
then
   source .bashc_real
fi

And:

if [ "$TERM" = "xterm" ]
then
   source .bashc_real
fi

However, nothing works. My shell terminal is bash, and I connect to sftp with filezilla.

Totor
  • 3,048
Joel G Mathew
  • 970

6 Answers6

28

Try doing this instead

if [ "$SSH_TTY" ]
then
   source .bashc_real
fi
Mike
  • 22,748
18

Mike's answer will probably work. But it's worth pointing out that you can accomplish this carefully selecting which startup files to put the verbose stuff in. From the bash man page:

When bash is invoked as an interactive login shell, or as a non-interactive shell with the --login option, it first reads and executes commands from the file /etc/profile, if that file exists. After reading that file, it looks for ~/.bash_profile, ~/.bash_login, and ~/.profile, in that order, and reads and executes commands from the first one that exists and is readable. The --noprofile option may be used when the shell is started to inhibit this behavior.

When an interactive shell that is not a login shell is started, bash reads and executes commands from ~/.bashrc, if that file exists. This may be inhibited by using the --norc option. The --rcfile file option will force bash to read and execute commands from file instead of ~/.bashrc.

The sftp/scp tools start an interactive non-login shell, so .bashrc will be sourced. Many distributions source .bashrc from .bash_profile or vice versa, so it can get confusing. A good trick for testing the cleanliness of your login environment is to ssh in with a command, which simulates the same way scp/sftp connect. For example: ssh myhost /bin/true will show you exactly what scp/sftp sees when they connect.

A simple demo:

insyte@mazer:~$ echo "echo Hello from .profile" > .profile
insyte@mazer:~$ echo "echo Hello from .bashrc" > .bashrc

sazerac:~ insyte$ ssh mazer /bin/true
Hello from .bashrc
sazerac:~ insyte$


insyte@mazer:~$ rm .bashrc


sazerac:~ insyte$ ssh mazer /bin/true
sazerac:~ insyte$

The first test will cause scp/sftp/rsync etc. to break. The second version will work just fine.

Community
  • 1
Insyte
  • 9,554
4

If you're using csh:

if ($?prompt)
  ... interactive stuff ...

And if it's bash:

if [[ $- == *i* ]]; then
  ... interactive stuff ...
fi

or alternatively using bash regular expressions:

if [[ $- =~ i ]]; then
  ... interactive stuff ...
fi

These lines should precede lines where you ouput/echo something back.

flying sheep
  • 103
user163384
  • 41
1

Mike's solution worked for me as well. But since my default shell is TCSH, I had to slightly edit the fix as follows (in .tcshrc):

if ( $?SSH_TTY ) then
    exec /bin/bash
endif

Just thought I would share for everyone's benefit.

Vijay Padiyar
  • 11
1

Here are the first lines of my (default) .bashrc file: 

# ~/.bashrc: executed by bash(1) for non-login shells.
# see /usr/share/doc/bash/examples/startup-files (in the package bash-doc)
# for examples

# If not running interactively, don't do anything
case $- in
    *i*) ;;
      *) return;;
esac

The check for an interactive session avoids messing up with SCP, SFTP or ssh remote-host command mode.

Without this, if your file .bashrc uses echo or some other stuff printing on stdout, you may get this kind of errors:

  • SFTP : Received message too long 168435779
  • SCP : protocol error: unexpected <newline>
Totor
  • 3,048
0

I like some of the other solutions mentioned here better, but I thought I throw out the solution that I currently use on my bash and csh VMs to prevent SFTP disconnects due to echo commands in my startup scripts, just in case anyone finds the information helpful.

In BASH:

if [ $TERM == "xterm" ] || [ $TERM == "xterm-256color" ]; then
  echo "Xterm display identified: echo enabled"
  echo_disable="0"
else
  echo_disable="1"
fi

# Use the following for all subsequent echo commands
if [ $echo_disable == 0 ]; then
 echo "Safe to display on Xterm"
fi

In csh:

if ($TERM == "xterm") then
  echo "Xterm display identified: echo enabled"
  set echo_disable = "0"
else
  set echo_disable = "1"
endif

# Use the following for all subsequent echo commands
if !( "$echo_disable" ) echo "Safe to display on Xterm"

It's a bit brute force, but it does work.

Bob Noonan
  • 1