[13176] in Athena Bugs
rsaix 7.7J: tcsh
daemon@ATHENA.MIT.EDU (Dan Christensen)
Fri Feb 3 15:45:53 1995
To: bugs@MIT.EDU
Date: Fri, 03 Feb 1995 15:45:44 EST
From: Dan Christensen <jdchrist@MIT.EDU>
System name: m2-225-13
Type and version: POWER 7.7J
Display type: POWER_Gt1
What were you trying to do?
Use the prompt variable to determine whether the shell is getting its
input from a terminal.
What's wrong:
/bin/csh (which is the tcsh) seems to always initially set the prompt
variable to "% ". The following shows an example of the problem:
m2-225-8[212]% cat test.csh
if ($?prompt) then
echo "Prompt is $prompt."
stty erase ^h
endif
m2-225-8[213]% /bin/csh -f < test.csh
Prompt is % .
stty: TXGETLD: Not a typewriter
m2-225-8[214]%
The input to /bin/csh was not interactive, but nevertheless the prompt
was set and stty gives an error. How can this be avoided? The same
thing happens if in addition the output is sent to a file. (Note
that the -f flag tells csh to ignore my dotfiles, so the prompt
isn't being set there.)
A consultant said:
My opinion is that this is a bug in tcsh. It should not be used to replace
csh, as there are many books and scripts that use just what you are trying
to use. This is pathological behavior. Run sendbug.
While you're at it, tell them tcsh still fails to set the echo mode when
you ctrl-Z out of olcr....
I like tcsh in general, so I'd like to continue using it, but I
would like a reliable way to tell if stty is going to crap out on
me.
What should have happened:
The prompt shouldn't be set unless the shell is getting its input from
the terminal.
Please describe any relevant documentation references:
Line 67 of the csh man page.
