Shell Programming and Scripting

Hi,
I have written a script file that first makes a ssh connection with the remote system and then does some job. My script file is as follows

Code:

#! /bin/sh
ssh 172.16.1.2 <<EOF
sa=`/usr/sbin/alternatives --config java </root/Desktop/1.txt 2>&1 | grep jdk1.6.0_05`
echo $sa
sa2=`echo $sa | sed -e 's/[^0-9]//g'`
sa3=`echo $sa2 | head -c 1 >/root/Desktop/2.txt` 
echo @sa3
echo "end"
EOF

The ssh connection is formed successfully. But sa is not printing anything. just a blank line
similarly sa3. But end is being printed. Both text files (1.txt and 2.txt)resides in the remote system. I know the problem is with this line

Code:

sa=`/usr/sbin/alternatives --config java </root/Desktop/1.txt 2>&1 | grep jdk1.6.0_05`

The command is not taking input from 1.txt which is residing on the remote system. Where am i going wrong.

The backticks get executed locally when the backticks are read. Use quoting to prevent that; see UNIX Shell Quote

Code:

#! /bin/sh
ssh 172.16.1.2 <<'EOF'  # note single quotes!
...
EOF

Of course, if some of those backticks need to be executed locally, you need to revise the script; perhaps refactor it to first calculcate those values locally, and then pass them to the remote script.

@sa3 is not a useful variable identifier in Bourne shell; is that a typo, or are you trying to use a Korn or Bash construct? (Anyway, $sa3 is going to be empty, since you redirect the output to a file.)