For Loop Containing Bash within an Expect Script

devUnix · 09-30-2014, 01:15 PM

My Expect script looks as shown below:

my.exp:

Code:

#!/usr/bin/expect -f
set M [lindex $argv 0]

spawn echo "stats <$M>" \| debugfs.ocfs2 -n /dev/HPEVA/OCFS2

expect "END"
send "q\r"

So, I am passing a parameter to the Expect script. Since debugfs.ocfs2 will sit at the "END" prompt line I am sending it "q\r" so that it can be closed / quitted automatically.

Here is what happens when I run the above script:

Code:

./my.exp M000000000000000065702b00000000
spawn echo stats <M000000000000000065702b00000000> | debugfs.ocfs2 -n /dev/HPEVA/OCFS2
stats <M000000000000000065702b00000000> | debugfs.ocfs2 -n /dev/HPEVA/OCFS2
send: spawn id exp4 not open
while executing
"send "q\r""
(file "./my.exp" line 8)

I have been looking up the error on Google and did not find any one particular cause of "spawn id exp4 not open". I do now understand that the previous command may have crashed or too early closed for the send command to send anything to it.

Please Note: The main problem / question / requirement is we have a large number of those values M00*(M000000000000000065702b00000000) and we need to run the debugfs command for each of them. So I wrote this small for loop script and called it a wrapper script that will call the expect script passing it a new value each time:

wrapper.sh:

Code:

for M in `grep Lockres /root/fslock |grep M0 |awk '{print $2}'`; do 

./my.exp $M ; 
done

The debugfs command shows the output and then sits at "END" that is why I am using Expect to send it "q\r".

Can I run that for loop in Expect itself and walk through each value?

Do I need to put an extra "echo" in this line?

Code:

spawn echo echo "stats <$M>" \| debugfs.ocfs2 -n /dev/HPEVA/OCFS2

so that it becomes:

Code:

echo stats <M000000000000000065702b00000000> | debugfs.ocfs2 -n /dev/HPEVA/OCFS2

I can't test that thing right now. Actually that is what my friend wants to do and he has the system so I will have to wait until morning when he goes to office.

ntubski · 09-30-2014, 10:05 PM

I don't know a lot about expect, but assuming

Code:

spawn echo "stats <$M>" \| debugfs.ocfs2 -n /dev/HPEVA/OCFS2

is equivalent to running

Code:

echo "stats <$M>" | debugfs.ocfs2 -n /dev/HPEVA/OCFS2

in the shell, your problem is that it won't accept any more input: echo will close the debugfs.ocfs2 input pipe after it finishes. You probably want something like this:

Code:

#!/usr/bin/expect -f
set M [lindex $argv 0]

spawn debugfs.ocfs2 -n /dev/HPEVA/OCFS2

send "stats <$M>\r"
expect "END"
send "q\r"

Or, if debugfs.ocfs2 isn't timing sensitive, perhaps you don't need expect at all, just a simple shell script:

Code:

for M in `grep Lockres /root/fslock |grep M0 |awk '{print $2}'`; do 
    { echo "stats <$M>"; echo "q"; } | debugfs.ocfs2 -n /dev/HPEVA/OCFS2; 
done

devUnix · 10-01-2014, 11:37 PM

Quote:

Originally Posted by ntubski

for M in `grep Lockres /root/fslock |grep M0 |awk '{print $2}'`; do
{ echo "stats <$M>"; echo "q"; } | debugfs.ocfs2 -n /dev/HPEVA/OCFS2;
done

That does not work. "END" still keeps sitting there for a manual "q" and "return key stroke".

I liked your expect script and think it does the work. Thanks a lot! I only needed to change the logic.