ssh服务器bash -c“ cd / tmp && git pull”，cd不起作用，需要先添加echo

Question

I'm on ubuntu 15.04, my version of ssh client is

OpenSSH_6.9p1 Ubuntu-2ubuntu0.2, OpenSSL 1.0.2d 9 Jul 2015

When I try to run the following command ssh admin@server bash -c 'cd /path/to/repo && git pull' the cd is not effective and i got

fatal: Not a git repository (or any of the parent directories): .git

However If I do

ssh admin@server bash -c 'echo test && cd /path/to/repo && git pull'

then it works

Already up-to-date.

Of course I'm well aware echo is not supposed to change anything but after trying several time, several days on several different servers (though all on debian) I'm now sure to have this error. On other servers I tried the command cd /tmp && pwd , and I got my home directory, and if i do echo toto && /tmp && pwd I go /tmp printed...

Answer 1

Unfortunately, ssh passes through a single command line string to $SHELL -c on the remote. Your quotes aren't being effective.

When you run

ssh admin@server bash -c 'cd /path/to/repo && git pull'

this is being run on the remote server (with $SHELL -c ):

bash -c cd /path/to/repo && git pull

So Bash is given single command ( cd ) and an unused argument, and then separately, you're also running git pull in the home directory.

On the other hand, when you run

ssh admin@server bash -c 'echo test && cd /path/to/repo && git pull'

this is being run on the remote server:

bash -c echo test && cd /path/to/repo && git pull

The first part is again useless, but the shell running the whole command then does cd /path/to/repo and git pull . Which works.

What you probably want to do is

ssh admin@server 'cd /path/to/repo && git pull'

Answer 2

The existing answer by ephemient is entirely correct in terms of cause.

To add an alternate solution -- one which works when your remote code contains constructs which sh -c will misinterpret -- consider:

repo=/path/to/repo                 ## here, this works even when your path contains
                                   ## nonprintable or otherwise surprising characters
printf -v repo_q '%q' "$repo"      ## ...because we're asking your local copy of bash
                                   ## to generate a quoted/escaped copy of the value
                                   ## that will 'eval' back to its original meaning
                                   ## when interpreted by bash

## to ensure that it's interpreted by bash, we pass 'bash -s' as the command to ssh
## with an *unquoted* heredoc (<<EOF, vs <<'EOF'), with the escaped value expanded
ssh admin@server 'bash -s' <<EOF
cd $repo_q && git pull
EOF