shell script for remote ssh login

sefaklc · 08-27-2007, 06:58 AM

hello all.
i am very new to write scripts.And i have a question.
How can i execute a script for remote ssh connection?

Code:

#!/bin/ksh

ssh 192.168.182.132
df -k 
pwd
echo $PATH

it works when i write them to terminal line by line ,but not with a script.
can you explain how can i do this? or some source for learning?

thank you

al2 · 08-27-2007, 07:55 AM

Are you using korn shell or bourne again shell? In case of the latter the first line in the script should be

Code:

#!/bin/bash

Make sure you have the rights to execute the script. In the terminal type

Code:

sudo chmode u+x filename

where filename is the name of your script file.

colucix · 08-27-2007, 08:30 AM

To run commands on the remote machine, you have to give commands in input to ssh. For simple commands you can use the syntax

Code:

ssh user@hostname <command>

where command is a string (better enclose in double quotes) containing the command you want to execute. Or you can use a "here document", e.g.

Code:

ssh user@hostname << LimitString
<command>
<command>
<command>
LimitString

where the commands placed after the ssh line and before the "LimitString" are executed on the remote machine. Actually you can use any string in place of "LimitString". You may also consider "private/public key authentication" to avoid typing password.

sefaklc · 08-28-2007, 06:58 AM

when i try

Code:

 
16 ssh  $ipaddress <<LimitString
 17 while (($i < ${#command[*]})) ; do
 18     ${command[$i]}  >>$outputfile || print "${command[$i]} :command not found\n">>$outputfile
 19     i=$i+1
 20     printf "****************************************\n" >>$outputfile
 21     done 
 22 exit
 23 LimitString

it gives me the error

Code:

Pseudo-terminal will not be allocated because stdin is not a terminal.

and it is waiting.

colucix · 08-28-2007, 07:21 AM

The error message is actually a warning. You can use option -T to disable pseudo-terminal allocation on the remote server

Code:

ssh -T $ipaddress << LimitString

Most likely it hangs for other reasons, depending by the commands you're trying to execute on the remote machine. Just a note:

Code:

exit
LimitString

The exit statement is not necessary here: the ssh session will terminate as soon as all commands are executed.

choogendyk · 08-28-2007, 09:03 PM

#!/bin/ksh is fine. I do most of my work in ksh. I realize a lot of people like bash, and there's nothing wrong with that either. They are related to one another.

As far as getting the commands to run on the remote server, it is true that the tty issue with a script can be a problem. I have been successfully doing this sort of thing for quite some time with the following sort of construct in scripts (just an example):

su - backup -c "ssh ${TAPESERVER} \"dd obs=64b of=${TAPDEV}\"";

In that example, the first set of quotes encloses the command which is to be executed by the backup user within the su. The second set of quotes inside which is made literal with the \ encloses the command that is being passed through the ssh to be executed on the remote machine. In this case this whole construct was following a pipe carrying the output of a ufsdump to the remote tape drive through ssh. I had ssh keys set up for the backup user so that this wouldn't get hijacked by the requirement to input a password. The entire script was being run under root, but I didn't want root keys between the servers. The backup user only had access to the tape drive.

In your example, you could do something like:

ssh 192.168.182.132 "df -k; pwd; echo $PATH";

and that should work straight out assuming that the user under whom you issue that line has keys set up for the connection.