brett@wjvax.UUCP (Brett Galloway) (02/27/86)
I ran across what appears to be strange behaviour in the Bourne shell (sh),
when one brings up a program using sh -c. Note that sh -c foo brings up
program foo running under /bin/sh. If one does this from the csh, as
sh -c foo &
as I understand it, that should bring up /bin/sh running foo, in the background,
but /bin/sh's stdin and stdout should still be connected to the control
terminal. Apparently, even when -c is used, sh thinks it is in interactive
mode.
That behaviour is questionable enough. What is even more peculiar is that
if one brings up sh -c foo NOT connected to a terminal, it still does
this! For example, do
sh -c foo </dev/null >&/dev/null &
from the csh. This puts /bin/sh -c foo with stdin, stdout, and stderr connected
to /dev/null, and runs it in the background (which is a nop in this case,
since /bin/sh is not connected to the terminal anyhow). It is clear that
/bin/sh should not assume that it is interactive, since /dev/null is not
a terminal, yet it appears to do so, insofar as it ignores SIGINT. Apparently,
the -c flag of sh effectively forces the -i (interactive) flag.
What I would like to know is whether this is a bug of /bin/sh, a (mis)feature,
or whether I am missing something. Please respond via mail, and I will
summarize.
Thanks (in advance).
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Brett Galloway
{pesnta,twg,ios,qubix,turtlevax,tymix,vecpyr,certes,isi}!wjvax!brett