[SOLVED] BASH while-do script does not execute another script

JoeTampa · 02-28-2014, 10:38 AM

I have a file that consists of a list of hosts and ports, space delimited:

10.2.4.11 443
10.55.22.77 4433
10.55.22.11 4444
10.55.22.53 443

I need to read these and run another bash script on each host and port. I have a script that reads the values and calls the script like so:

while read -r host port
do
./myscript $host $port
done < file

However, myscript never fires. I've tried calling it with bash ./myscript $host $port and with bash /path/to/myscript $host $port - but no joy.

Anyone have any ideas, or have a better way to do this?

suicidaleggroll · 02-28-2014, 10:55 AM

have you tried sticking an "echo" in front of your call to myscript to see if the while loop is even running and that host/port have the right values?

JoeTampa · 02-28-2014, 11:06 AM

Yep, in the form of

echo "Host: $host --- Port: $port"

..And I see proper output.

However, a similar line in the called script never produces output at all, so it appears to not be firing. Running the called script directly works fine.

grail · 02-28-2014, 11:10 AM

Try placing, set -xv, at the top of this script and see what is actually being executed.

Firerat · 02-28-2014, 11:12 AM

Well, if the echo works your while do loop is fine..

To help I think we need to see your "myscript" script

Please use bbcode tags

Code:

Like this

[code]
Like this
[/code]

schneidz · 02-28-2014, 11:17 AM

maybe the user doesnt have permissions to execute myscript ?

_Avyd · 02-28-2014, 11:54 AM

What about something like this:

Quote:

# Run command on multiple hosts (read host from hostlist)
for i in $(cat hostlist);
do
echo $i; ssh -o StrictHostKeyChecking=no -l root $i -C "echo command";
done

byau · 02-28-2014, 11:57 AM

Change myscript to something simple so you can take that out of the equation like

#!/bin/bash
echo "myscript $1 $2"

Is there any screen output? The first thing I would think is myscript is not executable but then it would tell you so when you try to call it

Firerat · 02-28-2014, 12:39 PM

Quote:

Originally Posted by _Avyd

What about something like this:

Please use code tags not quote

It would fail!

100% nothing wrong with the original while read loop

Yours will fail

Code:

# Run command on multiple hosts (read host from hostlist)
for i in $(cat hostlist);
do
    echo $i; ssh -o StrictHostKeyChecking=no -l root $i -C "echo command";
done

Since the list is host<space>port
Your for loop is

Code:

for i in host1 port1 host2 port2 host3 port3 ......

Like I said, nothing wrong with the while read in OP.

Problem, as has already been put out there, is likely

Script not executable ( or at least not for the user )

Incorrect/missing shebang ( #!/bin/bash )

Something else....

without seeing the script we don't know if the host and port are in the correct order
Just a guess.. no script to read ...

_Avyd · 02-28-2014, 01:01 PM

Quote:

Originally Posted by Firerat

Please use code tags not quote

It would fail!

100% nothing wrong with the original while read loop

Yours will fail

Code:

# Run command on multiple hosts (read host from hostlist)
for i in $(cat hostlist);
do
    echo $i; ssh -o StrictHostKeyChecking=no -l root $i -C "echo command";
done

Since the list is host<space>port
Your for loop is

Code:

for i in host1 port1 host2 port2 host3 port3 ......

Like I said, nothing wrong with the while read in OP.

Problem, as has already been put out there, is likely

Script not executable ( or at least not for the user )

Incorrect/missing shebang ( #!/bin/bash )

Something else....

without seeing the script we don't know if the host and port are in the correct order
Just a guess.. no script to read ...

I wrote "something like this" and didn't mean to copy paste it. Just an idea of implementation.

The code I copied is from my notes and is a working way of running commands on multiple server.

Firerat · 02-28-2014, 01:26 PM

Quote:

Originally Posted by _Avyd

I wrote "something like this" and didn't mean to copy paste it. Just an idea of implementation.

The code I copied is from my notes and is a working way of running commands on multiple server.

Well, it is a poor way of doing it
Ok, it is "ok" if you have one host per line, but it is still sloppy code

The correct way is the 'original' while read loop

Edit

http://mywiki.wooledge.org/BashGuide

Read that, and drop the bad habits you have picked up

rtmistler · 02-28-2014, 01:44 PM

Quote:

Originally Posted by JoeTampa

Yep, in the form of

echo "Host: $host --- Port: $port"

..And I see proper output.

However, a similar line in the called script never produces output at all, so it appears to not be firing. Running the called script directly works fine.

What do you mean by "not be firing"? You say the script called directly works fine; so it sounds as if it is executable, but then you make this "not be firing" statement which causes confusion.

How about you go back to the start. You have a script, post it within [code][/code] tags. Show the output from calling the script directly. Explain next, more clearly; what the problem is. Using a term like "not be firing" means nothing helpful. State instead what desired behavior or output you are not attaining.

_Avyd · 02-28-2014, 02:01 PM

Quote:

Originally Posted by Firerat

Well, it is a poor way of doing it
Ok, it is "ok" if you have one host per line, but it is still sloppy code

The correct way is the 'original' while read loop

Edit

http://mywiki.wooledge.org/BashGuide

Read that, and drop the bad habits you have picked up

I don't think there is a "correct" or "original" way of doing this as it's not a system like Windows.

The guide is great, thanks.

JoeTampa · 03-03-2014, 10:25 PM

...The set -xv did the trick.

The second item on each line had a CR ("\r") appended, and that totally threw off the second script, which exited.

I got around it by changing the read statement to have three arguments, and the CR got tacked on to the third bogus one.

Thanks for the help, everyone!

Joe

chrism01 · 03-04-2014, 05:12 AM

'\r' shouldn't be there; did you write that file on a Mac or possibly MS?
Use unix2dos to convert the file to *nix line endings only '\n' .