How do diff over ssh?

Question

How do I diff files/folders across machines provided that the only connectivity available is ssh?

Answer 1

You can do it with Bash's process substitution:

 diff foo <(ssh myServer 'cat foo')

or the same with

 ssh myServer cat foo | diff foo -

Or, if both are on remote servers:

diff <(ssh myServer1 'cat foo') <(ssh myServer2 'cat foo')

Answer 2

Finally I've found great solution: vimdiff

vimdiff /path/to/file scp://remotehost//path/to/file

thanks to http://linux.spiney.org/remote_diff_with_vim_and_ssh see also http://www.vim.org/scripts/script.php?script_id=1075 .

Answer 3

If you just want to see what files are different, rather than a diff of the actual files, then you can use rsync --dry-run

Answer 4

Here's another quick and dirty command line recipe. Unlike the chosen answer, it works inside of makefiles:

ssh [login]@[host] "cat [remote file]" | diff - "[local file]"

Answer 5

Use scp to bring the files to a common machine and diff them there?

Or, if you just want to know if the files are different or not, hash them with md5sum on each machine.

You could also look into something like SSHFS, but I don't know how well an algorithm like diff performs over that.

Answer 6

One way, if it is possible on your system would be to simply mount the remote filesystem with sshfs.

Answer 7

You can use rsync in dry run mode, as suggested briefly in another answer. It lists any files that are different.

For that, use the rvnc options (r=recursive, v=verbose, n= dry-run, c=checksum). With rsync in pull mode (rsync [OPTION...] [USER@]HOST:SRC... [DEST]), an example is:

rsync -rvnc root@182.18.158.207:/var/www/html/dev/ .

Remember, this provides no info on whether the local or remote file is newer. Just if they differ.

Answer 8

If you have sshfs and need to diff directories:

mkdir remote_path
sshfs user@host:/path/ remote_path
diff -r path remote_path

Answer 9

• on your local machine, make a recursive copy of the directory you want to diff. For instance:

  cp -R dir replica
  

• use rsync to replicate the remote directory over the local copy:

   rsync remote:/path/to/dir replica
  

• use diff to find difference between the local directory and the local replica of the remote one:

  diff dir replica
  

Answer 10

ssh-tools (debian) contains ssh-diff:

$ ssh-diff file [user@]hostname[:file]

Answer 11

Here is how I did it.

I used SFTP to the remote server and entered my username/pwd when prompted. Then I used the dir that was created in the .gvfs dir in my home directory in the diff command.

diff -r --brief /home/user dir/.gvfs/SFTP\ on\ freenas.local/path to dir/dir1 /path to local dir/dir2

Answer 12

This is a script that can help to diff local folder and remote folder.:

 #!/bin/bash

 LOCALFOLDER=/var/www/tee
 REMOTEFOLDER=$(ssh root@111.111.111.1 'ls -lA /hfs/tee'| grep -E '^total' | cut -d " " -f 2 > remotessh.txt)
 COMMAND=$(ls -lA $LOCALFOLDER | grep -E '^total' | cut -d " " -f 2 > localssh.txt)
 REM=$(cat remotessh.txt)
 LOCAL=$(cat localssh.txt)

 echo $LOCAL
 echo $REM

 if [ $REM -eq $LOCAL ]
 then
      echo Directories are the same
 else
      echo Directories are differnt
 fi

 #diff localssh.txt remotessh.txt | grep -E '^total' | cut -d " " -f 2

Answer 13

http://myfedora.co.za/2012/04/diff-two-remote-file-systems/

diff <(/usr/bin/ssh user1@192.168.122.1 'ls /opt/lib/') <(/usr/bin/ssh user2@192.168.122.1 'ls /tmp/') | grep -i ">" | sed 's/> //g'

Answer 14

Use sshfs mounted across ssh. It won't be all that fast, but you can use your full suite of tools that expect everything to be on a local filesystem. An alternative is NFS over a tunnel made with "ssh -w" (or other communications where ssh isn't the limitation).

Answer 15

You could also try generalizing the approach by creating a bash function, possibly in your ~/.bashrc:

myrdiff() { ssh root@"$1" cat "$2" | diff -s - "$2" ; }

then invoking it with a construct like:

myrdiff vm20-x86-64 /etc/gdm/Init/Default

By invoking diff with -s, this will also report if the files are identical.

Answer 16

I use | cat at the end of the command for interactive password prompts and sdiff because it is easier to read than diff :

So between local and remote, type :

sdiff -s cat myfile<(ssh server1 'cat myfile') | cat

and between two servers, type :

sdiff -s <(ssh server1 'cat myfile') <(ssh server2 'cat myfile') | cat

Answer 17

using grep

remote ip: 172.16.98.130
remote file: /etc/ssh/keys-root/authorized_keys
local file: ~/.ssh/id_rsa.pub

Now compare the contents of remote file with the local file using grep

grep -w "$(cat ~/.ssh/id_rsa.pub)" <<< $(sshpass -p "mypassword" ssh root@172.16.98.130 'cat /etc/ssh/keys-root/authorized_keys')

check the success status of the grep command

echo $?
# 0

Using this idea to setup SSH passwordless login:

if ! grep "$(cat ~/.ssh/id_rsa.pub)" <<< $(sshpass -p "mypassword" ssh root@172.16.98.130 cat /etc/ssh/keys-root/authorized_keys) &>/dev/null; then
  cat ~/.ssh/id_rsa.pub | sshpass -p "mypassword" ssh root@172.16.98.130 "cat >> /etc/ssh/keys-root/authorized_keys"
fi

ssh root@172.16.98.130

Note: Make sure sshpass package is installed for passing password non-interactively to ssh command.