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I need to get /mysqlsharedetails from all the MySQL servers. I have written a script using a while read loop, but it's getting the details of only the first server,

#!/bin/ksh
file="/home/mysqladm/server_list/server_list.txt"
# while loop
while IFS= read -r a
do
        # display line or do something on $line
        output=`ssh $a df -h | grep mysqlshare`
#echo $a,$output
echo $a ,$output >> /home/mysqladm/server_list/output.txt
done < "$file"

I have server_list.txt file in which there are two servers like,

server_name1,
server_name2,

it's going to server_name1 and doing df -h and getting out of script.  Why is the loop not working?

G-Man Says 'Reinstate Monica'
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harinath
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    Welcome to Stack Exchange.  What have you done to try to debug this?  What happens when you comment out the `ssh` and just print the server name?  By the way, you should always quote your shell variable references (e.g., `"$a"` and `"$output"`) unless you have a good reason not to, and you’re sure you know what you’re doing.  Also, just for clarity, you might want to change `\`…\`` to `$(…)` — see [this](http://unix.stackexchange.com/q/5778/80216), [this](http://unix.stackexchange.com/q/147838/80216), and [this](http://unix.stackexchange.com/q/104119/80216).  And please indent correctly. – G-Man Says 'Reinstate Monica' Dec 16 '15 at 06:33
  • I am new to scripting, trying from my end to get it.Do loop when we use while read in it? i used ====================================for server in `cat /home/mysqladm/server_list/ms_mysql_all_servers_list` ; do share=`ssh $server df -h /mysqlshare*` $share >>/home/mysqladm/server_list/share.txt done...............this one is working fine but unable to get it using while loop. – harinath Dec 16 '15 at 06:58

1 Answers1

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SSH tries to read all the remaining stdin, so it breaks the loop. You need to connect it's stdin to null with < /dev/null or do something else like that.

Here is how I would write script to achieve that:

#!/bin/bash
IFS=,
file=servers.txt
logfile=log.txt
while read server
do
        ssh $server<<<"df -h | grep mysqlshare" 2>&1>>$logfile
done < $file
StefanR
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