SSH for loop executing command script

Question

I have a script to get server health from multiple servers like this:

#!/bin/bash
for ip
do
    ssh 192.168.1.209 ssh root@$ip cat /proc/loadavg | awk '{print $1}' #CPU Usage
    free | grep Mem | awk '{print $3/$2 * 100.0}' #Memory Usage
    df -khP  | awk '{print $3 "/" $2}' | awk 'FNR == 2' #Disk Space
    df -kihP  | awk '{print $3 "/" $2}' | awk 'FNR == 2' #Inode Space
    date +'%d %b %Y %r %Z' #Datetime
    ps -eo user,pid,pcpu,pmem,args|sort -nr -k3|head -5 #Process
done

The 209 is acting like a portal on my network so I have to ssh to it 1st in order to access other servers. By typing this command on terminal:

./my_script.sh 192.168.1.210 192.168.1.211 192.168.1.212

I would like to get each of the command output (ps,date etc) from each server. Expected output for 2 servers should be like:

0.11 #health from server 1
4.82577
1.7G/49G
46K/49M
27 Dec 2016 05:34:57 PM HKT
root        93  0.0  0.0 [kauditd]
root         9  0.0  0.0 [rcuob/0]
root      8740  0.0  0.0 ifstat --scan=100
root       829  0.0  0.0 /usr/sbin/wpa_supplicant -u -f /var/log/wpa_supplicant.log -c /etc/wpa_supplicant/wpa_supplicant.conf -u -f /var/log/wpa_supplicant.log -P /var/run/wpa_supplicant.pid
0.00  #health from server 2
4.82422
1.7G/49G
46K/49M
27 Dec 2016 05:34:57 PM HKT
root        93  0.0  0.0 [kauditd]
root         9  0.0  0.0 [rcuob/0]
root      8740  0.0  0.0 ifstat --scan=100
root       829  0.0  0.0 /usr/sbin/wpa_supplicant -u -f /var/log/wpa_supplicant.log -c /etc/wpa_supplicant/wpa_supplicant.conf -u -f /var/log/wpa_supplicant.log -P /var/run/wpa_supplicant.pid

The problem that I'm facing is that It seems like it's only getting the health info from one server only. Why is that? Is it because I cannot do SSH like this? I'm using PHP exec() function to execute the script btw, to further format and display it on my local page.

oh i forgot to mention, the 209 is acting like a portal on my network. I can only ssh to 210,211 etc from 209. so Im actually ssh to 209 first — Lim SY
– Lim SY, Commented Dec 27, 2016 at 9:57

Inian · Accepted Answer · 2016-12-27 10:37:51Z

1

The best way to do that in bash is to use Here Documents << and run a loop over each of the arguments ($@) passed to the script as

for ip in "$@"
do
    ssh 192.168.1.209 ssh root@"$ip" <<-EOF
    cat /proc/loadavg | awk '{print $1}'
    free | grep Mem | awk '{print $3/$2 * 100.0}' 
    df -khP  | awk '{print $3 "/" $2}' | awk 'FNR == 2'
    df -kihP  | awk '{print $3 "/" $2}' | awk 'FNR == 2'
    date +'%d %b %Y %r %Z'
    ps -eo user,pid,pcpu,pmem,args|sort -nr -k3|head -5
    EOF
done

Remember to NOT have leading or trailing whitespaces before header <<-EOF and the final EOF, use tab-space for the terminating EOF.

You can run the script now as

./my_script.sh 192.168.1.210 192.168.1.211 192.168.1.212

Also you can wrap the contents of the script in a simple bash script and run it in one shot as

#!/bin/bash

cat /proc/loadavg | awk '{print $1}'
free | grep Mem | awk '{print $3/$2 * 100.0}' 
df -khP  | awk '{print $3 "/" $2}' | awk 'FNR == 2'
df -kihP  | awk '{print $3 "/" $2}' | awk 'FNR == 2'
date +'%d %b %Y %r %Z'
ps -eo user,pid,pcpu,pmem,args|sort -nr -k3|head -5

Call the above script as commandlist.sh and call it inside the for-loop as

ssh 192.168.1.209 ssh root@"$ip" 'bash -s ' < /path-to/commandlist.sh

edited Dec 27, 2016 at 10:37

answered Dec 27, 2016 at 10:00

Inian

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6 Comments

Lim SY Over a year ago

I am getting ./health.sh: line 14: warning: here-document at line 4 delimited by end-of-file (wanted `EOF') ./health.sh: line 15: syntax error: unexpected end of file

Lim SY Over a year ago

It is still the same, btw "<<-EOF" should be "<< EOF"?

Inian Over a year ago

@LimSY: Also for the terminating token EOF before done, do not use <space> character, use <tab> and can you try once?

Lim SY Over a year ago

Now it does not have any error, but without any output though. i have to press ctrl+c to cancel

Inian Over a year ago

@LimSY: Can you try the last suggestion from my answer? with the commands in a single file

|

Dario · Accepted Answer · 2016-12-28 00:18:36Z

Well, I’d do something completely different.

First I’d write a commandlist.sh script as follows (not forgetting to make it executable...):

#!/bin/bash
echo "# Health from $(hostname)"
cat /proc/loadavg | cut -d' ' -f1 #CPU Usage
free | grep Mem | awk '{print $3/$2 * 100.0}' #Memory Usage
df -khP  | awk 'FNR == 2 {print $3 "/" $2}' #Disk Space
df -kihP  | awk 'FNR == 2 {print $3 "/" $2}' #Inode Space
date +'%d %b %Y %r %Z' #Datetime
ps -eo user,pid,pcpu,pmem,args|sort -nr -k3|head -5 #Process

(mmh.. I would produce the same output with very different code, but since it’s your script I’ve only edited out a couple of superfluous awk invocations.)

Then, I’d place it on the 209, where I’d also install GNU parallel. Separately, I’d write the file ~/.parallel/sshloginfile as follows:

1/192.168.1.210
1/192.168.1.211
1/192.168.1.212

and I’d run the command

ssh 192.168.0.209 parallel -S .. --nonall --bf commandlist.sh ./commandlist.sh

Have a good look at man parallel for more possibilities.

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