if statement test string for value.

casperdaghost · 06-18-2012, 12:31 AM

sample of my /etc/host file:

Code:

carcapser  192.168.1.6  #prod
ashcapser  192.168.1.7  #prod
carghost   192.168.1.8  #prod
ashghost   192.168.1.9  #prod
carboo     192.168.1.10 #prod
ashboo     192.168.1.11 #prod
carcat     192.168.1.12 #prod
ashcat     192.168.1.13 
carshreik  192.168.1.14 #prod
ashshriek  192.168.1.15

So the script will ssh to any line with a #prod on on it - and (here is where the trouble is)
anything named capser or ghost i want to run one script, and anything else I want to run another.
having trouble though.

Code:

#!/bin/bash

 for i in $(grep "#prod" /etc/hosts | awk '{print $2}')
 do
 ssh -q casper1@$i <<here
 if [ hostname != "casper|ghost' ] ;
 then
  hostname
  echo "/data/noc/crons/ping_gw_test_mcore.sh"
  /data/noc/crons/ping_gw_test_mcore.sh

 echo " "
 else
 hostname
 echo "/data/noc/crons/ping_gw_test.sh"
 /data/noc/crons/ping_gw_test.sh
 echo " "
 fi
here
 done

is there something wrong with the if statment evaluation?

NevemTeve · 06-18-2012, 01:19 AM

Code:

grep '#prod' /etc/host | while read ip name comment; do 
...
done

grail · 06-18-2012, 01:32 AM

I am a little confused ... isn't the first column in the file the hostname? Why not test prior to ssh?

As for the test, my first would be to say using [[]] over [] can often help eliminate quirky errors, but as for the test itself I see a couple of issues:

1. Calling the command straight as you have the test is now comparing if the string 'hostname' is not equal to the other side (tip: think of how you normally get command output)

2. Is it likely that any of the hosts you are going to are called 'casper|ghost', ie the entire string including the pipe? I would guess not. maybe you are thinking of doing a regex match
which would then need to use =~

NevemTeve · 06-18-2012, 04:17 AM

Note: Having a file named '/etc/host' is a very bad idea. It could very well be /usr/local/etc/someproject.hostlist or ~casper/someproject.hostlist

KenJackson · 06-18-2012, 05:58 AM

For a partial match of names, the case statement is best. It matches just like filenames are wildcarded on the command line (not regular expressions).

I didn't try to run it, but this should work:

Code:

#!/bin/bash

grep '#prod' /etc/host | while read IP NAME comment; do 
    case $NAME in
        *casper|*ghost)
            SCRIPT="/data/noc/crons/ping_gw_test.sh"
            ;;
        *)  SCRIPT="/data/noc/crons/ping_gw_test_mcore.sh"
            ;;
    esac
    ssh -q casper1@$IP "hostname; echo $SCRIPT; $SCRIPT"
    echo
done

casperdaghost · 06-19-2012, 01:29 AM

I have given up on making the <<here document work - for now.

This works - but only sends the script via ssh's to the first host in the list then exits.

Code:

#!/bin/bash
grep '#prod' /etc/hosts | while read IP Name comment;
do
case $NAME in
*casper|*ghost) SCRIPT="/data/noc/crons/ping_gw_test_mcore.sh" ;;
*)SCRIPT="/data/noc/crons/ping_gw_test.sh" ;;
esac
ssh -q casper@$IP "hostname; echo "$SCRIPT" ; $SCRIPT"
echo
done

casperdaghost · 06-19-2012, 08:28 AM

When I just print out ip's from the while loop

Code:

casper@casperbox:~$ more /home/casper/case_exp
#!/bin/bash
grep '#prod' /etc/hosts | while read IP Name comment;
do
echo $IP
sleep 1
done

so what I need if for the care statement to be applied to each ip from the /etc/hosts list.

Code:

this is what I get 
168.18.40.49
168.29.80.18
168.29.100.11
168.29.80.16
168.29.80.29
168.29.80.23
168.18.40.18
168.18.60.11
168.18.40.16
168.18.40.38
168.18.40.39
168.18.60.11
168.18.57.11
168.29.97.11
168.18.40.46
168.29.80.47
168.18.72.11
168.18.72.12
168.18.72.13
168.18.72.35
168.18.72.31
168.18.50.20
168.18.50.21
192.168.139.97
168.18.40.49
168.18.50.20

NevemTeve · 06-19-2012, 08:57 AM

Somewhere during the saga you switched from /etc/host (name ip comment) to /etc/hosts (ip name comment). Was that intentional?

casperdaghost · 06-19-2012, 09:06 AM

i am at work now ... the work file i deal with is /etc/hosts .. at home i have a copy of the work file i use for remote connection .. /etc/host

ntubski · 06-19-2012, 09:26 AM

Quote:

Originally Posted by casperdaghost

This works - but only sends the script via ssh's to the first host in the list then exits.

The ssh commmand is reading stdin so it swallows all the data from grep, you can fix it by redirecting from /dev/null:

Code:

ssh -q casper@$IP "hostname; echo "$SCRIPT" ; $SCRIPT" < /dev/null
# or use -n option for ssh which does the same
ssh -n -q casper@$IP "hostname; echo "$SCRIPT" ; $SCRIPT"

Quote:

man ssh(1)
...
-n

Redirects stdin from /dev/null (actually, prevents reading from
stdin). This must be used when ssh is run in the background. A
common trick is to use this to run X11 programs on a remote
machine. For example, ssh -n shadows.cs.hut.fi emacs & will
start an emacs on shadows.cs.hut.fi, and the X11 connection will
be automatically forwarded over an encrypted channel. The ssh
program will be put in the background. (This does not work if
ssh needs to ask for a password or passphrase; see also the -f
option.)

casperdaghost · 06-19-2012, 01:56 PM

the -n works great!!!!
and that solves alot of problems that i have been having scripting with ssh.
that is one of the reasons that i originally put this script in the here document.

I really appreciate you help guys - all of you