[Tcsh] Independent stderr redirection through /dev/std[in][out].

[M G P]

I've come across certain situations where the traditional sub-shell method doesn't always solve the problem of independent stderr redirection, resulting in creation of a FIFO.

The following snippet allows for independent stderr redirection.

( ( ( echo ok ; no ) > /dev/stdin ) >& /dev/null < /dev/stdout ) | ( echo "$<" )

Sadly, seems to break at times, resulting in blank output. Likely a bug in Tcsh or the operating system?

I don't know the history on the /dev/std[in][out][err] files. How much standard are these files?

Here's an example program which is difficult for the traditional method.

if ( ! "$?main" ) then
  set main = "$cwd/$0"
  ( exit ( { ( ( ( grep ok * | \
  source "$main" ) > /dev/stdin ) \
  < /dev/stdout >& /dev/null ) } ) ) | \
  ( set file = "$<" ; \
  exit ( "$file" == ) && \
  echo "$file:s/://" ) || \
  exit -1
  exit
endif

set file = "$<"
while ( "$file" != )
  if ( "$file" =~ "${1}:*" ) then
    glob $file:x
    exit 1
  endif
  set file = "$<"
end
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