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Full Discussion: Expect - Interact output hangs when large output
Top Forums Shell Programming and Scripting Expect - Interact output hangs when large output Post 302229632 by natedog on Wednesday 27th of August 2008 11:21:42 AM
Old 08-27-2008
Expect - Interact output hangs when large output
Hello,
I have a simple expect script I use to ssh to a workstation. I then pass control over to the user with interact.
This script works fine on my HP and Mac, but on my Linux Desktop, I get a problem where the terminal hangs when ever I execute a command in the interact session that requires a fairly large output to be dumped.

For example, if I run "ls" on a directory with a lot of files, it seems like the output just loops indefinitely (I see the files in the directory repeatedly) and I don't get control back. I can't even stop it with ctrl-c , I need to kill the process.

I tried setting option: interact -nobuffer with no success. I have a feeling it has to do with the speed of the output, or the buffer size of interact. Any suggestions?

Below is my expect script:
#!/usr/bin/expect

if {[llength $argv] < 1 } {

puts "Incorrect arguments. Enter following syntax:\n"
puts " tn <node to telnet to> \n\r"
puts "Example: \n"
puts " tn ottud023 \n\r\n\r"
exit 1

}

set wsname [lindex $argv 0]
set displayno 0
set timeout 15

exec xhost +

spawn ssh $wsname -l $UserID
set spwnid1 $spawn_id

expect {
-i $spwnid1
"login" {
send "$UserID\n"
}
"Password" {
send "$Passwd\n"
}
"password" {
send "$Passwd\n"
}
timeout {
send_user "TIMEOUT\n"
}
}

# clear out buffer
expect -re {.*} {}

interact -nobuffer

Last edited by natedog; 08-27-2008 at 03:50 PM..
 

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LEARN ABOUT REDHAT

script

SCRIPT(1)						    BSD General Commands Manual 						 SCRIPT(1)

NAME

     script -- make typescript of terminal session

SYNOPSIS

     script [-a] [-f] [-q] [-t] [file]

DESCRIPTION

     Script makes a typescript of everything printed on your terminal.	It is useful for students who need a hardcopy record of an interactive
     session as proof of an assignment, as the typescript file can be printed out later with lpr(1).

     If the argument file is given, script saves all dialogue in file.	If no file name is given, the typescript is saved in the file typescript.

     Options:

     -a      Append the output to file or typescript, retaining the prior contents.

     -f      Flush output after each write. This is nice for telecooperation: One person does `mkfifo foo; script -f foo' and another can super-
	     vise real-time what is being done using `cat foo'.

     -q      Be quiet.

     -t      Output timeing data to standard error. This data contains two fields, separated by a space. The first field indicates how much time
	     elapsed since the previous output. The second field indicates how many characters were output this time. This information can be used
	     to replay typescripts with realistic typing and output delays.

     The script ends when the forked shell exits (a control-D to exit the Bourne shell (sh(1)), and exit, logout or control-d (if ignoreeof is not
     set) for the C-shell, csh(1)).

     Certain interactive commands, such as vi(1), create garbage in the typescript file.  Script works best with commands that do not manipulate
     the screen, the results are meant to emulate a hardcopy terminal.

ENVIRONMENT

     The following environment variable is utilized by script:

     SHELL  If the variable SHELL exists, the shell forked by script will be that shell. If SHELL is not set, the Bourne shell is assumed. (Most
	    shells set this variable automatically).

SEE ALSO

     csh(1) (for the history mechanism), replay(1).

HISTORY

     The script command appeared in 3.0BSD.

BUGS

     Script places everything in the log file, including linefeeds and backspaces.  This is not what the naive user expects.

Linux								   July 30, 2000							     Linux
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