loop port variable to connect to multiple computers

Question

I have a few raspberry pi's creating reverse ssh tunnels on an ssh server. From that server I can connect on all the raspberry pi's. I want to create a bash script that will run on this ssh server, collect some information from all the raspberry pi's and generate an html report. I have something working already, it only connects on a single raspberry pi. I need to somehow loop it, so that it will connect on all the raspberry pi's.

The variable that must be looped somehow is $port because each raspberry pi connects on a unique port on the ssh server, and its from that port that the server can connect back on the raspberry pi's.

I'm guessing it will have to be something like... for each $port in ports.txt perform the following commands and put the results in the html table

#!/bin/bash

cpu="$(ssh -o StrictHostKeyChecking=no $user@localhost -p $port echo $[100-$(vmstat|tail -1|awk '{print $15}')]"%")"
dsk="$(ssh -o StrictHostKeyChecking=no $user@localhost -p $port df -h /dev/mmcblk0p2 | awk 'NR>1{print $5}')"
mem="$(ssh -o StrictHostKeyChecking=no $user@localhost -p $port free | grep -e-/+ | awk '{print $3/($3+$4) * 100.0 ''}' | cut -d '.' -f1)"
tmp="$(ssh -o StrictHostKeyChecking=no $user@localhost -p $port /opt/vc/bin/vcgencmd measure_temp | sed -e 's/temp=//')"
mda="$(ssh -o StrictHostKeyChecking=no $user@localhost -p $port /bin/ls -R -l /$user/media | /usr/bin/wc -l)"

echo '<html>'
echo '<head>'
echo '<title>BeatBox Report</title>'
echo '</head>'
echo '<body>'
echo '<table border="1" align="center">'
echo     '<tr>'
echo         '<td></td>'
echo         '<td>CPU Usage</td>'
echo         '<td>Disk Usage</td>'
echo         '<td>Memory Usage</td>'
echo         '<td>Temperature</td>'
echo         '<td>Media Count</td>'
echo     '</tr>'
echo     '<tr>'
echo         '<td>Client001</td>'
echo         "<td align="center">$cpu</td>"
echo         "<td align="center">$dsk</td>"
echo         "<td align="center">$mem%</td>"
echo         "<td align="center">$tmp</td>"
echo         "<td align="center">$mda</td>"
echo     '</tr>'
echo     '<tr>'
echo         '<td>Client002</td>'
echo         "<td align="center">$cpu</td>"
echo         "<td align="center">$dsk</td>"
echo         "<td align="center">$mem%</td>"
echo         "<td align="center">$tmp</td>"
echo         "<td align="center">$mda</td>"
echo     '</tr>'
echo     '<tr>'
echo         '<td>Client003</td>'
echo         "<td align="center">$cpu</td>"
echo         "<td align="center">$dsk</td>"
echo         "<td align="center">$mem%</td>"
echo         "<td align="center">$tmp</td>"
echo         "<td align="center">$mda</td>"
echo     '</tr>'
echo     '</table>'
echo '</body>'
echo '</html>'

at the beginning of your script insert this line for port in $(cat ports.txt); do and at the end of it, insert line done. As long as all ports are in ports.txt file, you are good to go — MelBurslan, Apr 06 '16 at 17:08

Guido · Answer 1 · 2016-04-06T19:14:16.923

0

I suggest to refactor your existing code into a function (get_stats) and call this function from a while loop which reads each port number from your port file (assuming one number per line):

#!/bin/bash

function get_stats {
    local port=$1

    local cpu="..."
    local dsk="..."
    # ... remaining assignments ...

    # Output an HTML table row for this client
    echo     '<tr>'
    echo         "<td>Client on port $port</td>"
    echo         "<td align='center'>$cpu</td>"
    # ... echo remaining vars in similar fashion ...
    echo     '</tr>'
}

# Print HTML intro
echo '<html>'
# ... more html code until end of table header ...
echo         '<td>Media Count</td>'
echo     '</tr>'

# Print statistics for each client in turn - one table row per client
portfile='ports.txt'
while read port; do
    get_stats $port
done <$portfile

# Print HTML outro
echo     '</table>'
echo '</body>'
echo '</html>'

edited Apr 06 '16 at 19:14

answered Apr 06 '16 at 17:14

Guido

4,114

I tried it like this, but the results are all the same. Like, it only connects to the first port in ports.txt and fills the information for all clients. http://paste.ofcode.org/fP4giceZv6mQPyvx5U8gnA – aristosv Apr 06 '16 at 18:55
@aristosv That's because you printed the entire HTML page in each call of get_stats. See my updated example: first, print the HTML header and table beginning outside the loop. Then, only print a single <tr> table row each time get_statsis called. Finally (outside the loop again), close the table and print the remaining HTML. – Guido Apr 06 '16 at 19:17
I have 3 ports in ports.txt but I only get one row in the html report. What did I do wrong? http://paste.ofcode.org/i4d4PsKyhHgQAKbjXkEnhw – aristosv Apr 07 '16 at 04:53
@aristosv If I take your script and replace all 5 ssh calls by local cpu=$(echo testcpu) etc. for debugging, I get 3 HTML rows as expected. See http://paste.ofcode.org/jYEbsQwknnvfm7FUK9c3Aq . It therefore seems to me that there is some problem with at least one of the ssh calls. I suggest to focus on each one in turn (starting with cpu) and comment the other local assignments out to see if one of them causes an error. – Guido Apr 07 '16 at 08:47
Your code works. But as soon as I define any one of the ssh calls it only shows 1 client. I tried them all one by one. Then all of them. Same result. As soon as I commented them all out, it showed more than one again. – aristosv Apr 07 '16 at 16:14
this is the code http://paste.ofcode.org/atpQhqCivhYneYWKnPSAM3 – aristosv Apr 07 '16 at 16:16
even if I use simple commands like "ssh -o StrictHostKeyChecking=no root@localhost -p $port pwd" and "ssh -o StrictHostKeyChecking=no root@localhost -p $port ls" it still doesn't work. – aristosv Apr 07 '16 at 18:54
@aristosv If you enter a command like user="myusername";port="22";echo "$(ssh -o StrictHostKeyChecking=no $user@localhost -p $port /bin/ls)"on the command line, does it work without having to enter a password? (in that case, something could be wrong with your authentication setup in .authorized_keys on the remote system, which is where you would have to look next). – Guido Apr 07 '16 at 19:47
the commands on the command line (and in the script) work, and return results. But only for one row in html (one client). As soon as I remove all commands, then all rows appear. – aristosv Apr 08 '16 at 04:24
ok I removed the ssh keys to prevent it from authenticating, and it created the rows for each port. of course I got error messages for failed authentication for each port attempt, but at least it created the rows. Could the problem be that its connecting on a host, and then trying to authenticate from that host to the next port, instead of trying to authenticate from the SSH server? – aristosv Apr 08 '16 at 05:13

loop port variable to connect to multiple computers

1 Answers1