*BSD News Article 33847


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From: ron@argus.lpl.Arizona.EDU (Ron Watkins)
Newsgroups: comp.unix.questions,comp.unix.admin,comp.unix.misc,comp.unix.bsd
Subject: waiting for tty input???
Date: 29 Jul 1994 13:49:32 GMT
Organization: Lunar and Planetary Lab, U of AZ
Lines: 33
Distribution: world
Message-ID: <31b1dc$36g@news.CCIT.Arizona.EDU>
NNTP-Posting-Host: argus.lpl.arizona.edu
Keywords: tty

I have a shell script which is suposto run a tape drive on a remote host.
Inside the script, we were doing things like:

mt -f /dev/nrst1 rewind
dd if=xxx of=/dev/nrst1 obs=28800
etc...

We modified the script to do the following format of commands:

rsh host mt -f /dev/nrst1 rewind
dd if=xxx | rsh host dd of=/dev/nrst1 obs=28800
etc...

Problem is, it seems that on every mt rewind command, the script pauses
and produces a 'waiting for tty input' message. Thus, I can't make the script
work without some form of user intervention. These scripts are normally run
in the background using 'script &' syntax under csh. Moving the job to
the foreground 'fg' sometimes sems to work but not always. Anyhow,, this is
unacceptable. These jobs are often submitted and then the terminal is logged 
out due to the long time required to write the tape.
I need to get answers to some questions regarding this:

1) Why does this happen?

2) How can I prevent this from happening?

Thanks,
			Ron Watkins
--
Ron Watkins    [ron@argus.lpl.arizona.edu]    /            /~~~~)     /
931 Gould-Simpson                            /            /____/     /
University of Arizona                       /            /          /
Tucson AZ. 85721 -- (602) 621-8606         (____ unar & / lanetary (____ ab.