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Full Discussion: Special Character issue in Expect Utility (Tcl)
Top Forums Shell Programming and Scripting Special Character issue in Expect Utility (Tcl) Post 302918775 by Mahesh Desai on Thursday 25th of September 2014 01:20:21 PM
Old 09-25-2014
Special Character issue in Expect Utility (Tcl)
Hi,

I have written a unix expect utility "ssh-login.exp" which connects (ssh) to remote host and execute some shell script. I am calling this "ssh-login.exp" utility from another shell script.

"ssh-login.exp" takes username, password, host and shell script path to execute on remote host. All works fine for alphanumeric passwords. If password contains special characters e.g. "$", "ssh-login.exp" doesn't work. I have already added logic to add escape character right before any special characters in password string.

e.g. for password string "welcome$123" and I send "welcome\$123".

The issue is when expect utility "ssh-login.exp" sends password to remote host, it prepends '{' and appends '}' to password string if password contains any special characters. if password doesn't have any special characters then it sends password without '{' and '}' and works fine.

e.g. for password "welcome$123" expect program sends "{welcome\$123}", in fact it should send "welcome\$123" (without '{' and '}' ). If password is "{welcome\$123}" remote machine don't allow the entry because of wrong password as it is '{' and '}'.

So I am trying to find out a way to get rid of '{' and '}' from password string before sending it to remote host if password contains any special characters.

Here is my expect script : "ssh-login.exp":

Code:
#!/usr/bin/expect -f

set username [lrange $argv 0 0]
set password [lrange $argv 1 1]
set host [lrange $argv 2 2]
set script [lrange $argv 3 3]

set prompt "*$*"

set scriptIO  [open ./$script r]
set scriptContents [read -nonewline $scriptIO]
close $scriptIO

spawn ssh -q -o StrictHostKeyChecking=no $username@$host

#match_max 100000

while (1) {
        expect {
                "no)? " {
                        send -- "yes\r"
                        send -- "\r"
                }
                "*?assword:*" {
                        send -- "$password\r"
                        send -- "\r"
                }
                "$prompt" {
                        send -- "pwd\r"
                        send -- "\r"
                        break;
                }
        }
}

send -- "\r"

send -- "$scriptContents\r"

send -- "exit\r"

expect eof

Please let me know if someone has already faced this issue and were able to resolve it.

Thanks,
Last edited by Mahesh Desai; 09-25-2014 at 02:26 PM..
 

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LEARN ABOUT FREEBSD

ssh-copy-id

SSH-COPY-ID(1)						    BSD General Commands Manual 					    SSH-COPY-ID(1)

NAME

     ssh-copy-id -- copy public keys to a remote host

SYNOPSIS

     ssh-copy-id [-lv] [-i keyfile] [-o option] [-p port] [user@]hostname

DESCRIPTION

     The ssh-copy-id utility copies public keys to a remote host's ~/.ssh/authorized_keys file (creating the file and directory, if required).

     The following options are available:

     -i file
	     Copy the public key contained in file.  This option can be specified multiple times and can be combined with the -l option.  If a
	     private key is specified and a public key is found then the public key will be used.

     -l      Copy the keys currently held by ssh-agent(1).  This is the default if the -i option was not specified.

     -o ssh-option
	     Pass this option directly to ssh(1).  This option can be specified multiple times.

     -p port
	     Connect to the specified port on the remote host instead of the default.

     -v      Pass -v to ssh(1).

     The remaining arguments are a list of remote hosts to connect to, each one optionally qualified by a user name.

EXIT STATUS

     The ssh-copy-id utility exits 0 on success, and >0 if an error occurs.

EXAMPLES

     To send a specific key to multiple hosts:
	   $ ssh-copy-id -i /path/to/keyfile.pub user@host1 user@host2 user@host3

HISTORY

     The ssh-copy-id utility was written by Eitan Adler <eadler@FreeBSD.org> as a drop-in replacement for an existing utility included with
     OpenSSH.

BSD
								 February 28, 2014							       BSD
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