Forward exit status after pipe

[Andrew Greensted]

Hi All,

I've written a simple c program that reads stdin, adds highlighting to
particular words and outputs the result to stdout.

I invoke it as follows (where xil-highlight is my program):

build | xil-highlight

I'm using this within a make file. The problem is, if the build part
fails, the exit status is not picked up by make and does not exit.

Is there some way I can 'read' the exit status of build and forward that
to the exit status of my xil-highlight program.

Thanks
Andy

[Walter Roberson]

In article <g6**********@netty.york.ac.uk>,
Andrew Greensted <aj****@ohm.york.ac.ukwrote:

>I've written a simple c program that reads stdin, adds highlighting to
particular words and outputs the result to stdout.

>I invoke it as follows (where xil-highlight is my program):

build | xil-highlight

>I'm using this within a make file. The problem is, if the build part
fails, the exit status is not picked up by make and does not exit.

That is not a C issue; it is a make issue or a shell issue.

>Is there some way I can 'read' the exit status of build and forward that
to the exit status of my xil-highlight program.

Not within standard C, not without using operating-system specific
extensions. The C language knows nothing about multiple programs
or pipes.

Either your C program xil-highlight will not get started or it
will get started but will detect EOF when 'build' has nothing to send it.
Your C program should not have to depend upon finding the status of
'build'.
--
"Every intellectual product must be judged from the point of view
of the age and the people in which it was produced."
-- Walter Horatio Pater

[Keith Thompson]

Andrew Greensted <aj****@ohm.york.ac.ukwrites:

I've written a simple c program that reads stdin, adds highlighting to
particular words and outputs the result to stdout.

I invoke it as follows (where xil-highlight is my program):

>build | xil-highlight

I'm using this within a make file. The problem is, if the build part
fails, the exit status is not picked up by make and does not exit.

Is there some way I can 'read' the exit status of build and forward
that to the exit status of my xil-highlight program.

Try comp.unix.shell.

--
Keith Thompson (The_Other_Keith) ks***@mib.org <http://www.ghoti.net/~kst>
Nokia
"We must do something. This is something. Therefore, we must do this."
-- Antony Jay and Jonathan Lynn, "Yes Minister"

[Antoninus Twink]

On 28 Jul 2008 at 14:46, Andrew Greensted wrote:

I invoke it as follows (where xil-highlight is my program):

build | xil-highlight

I'm using this within a make file. The problem is, if the build part
fails, the exit status is not picked up by make and does not exit.

Is there some way I can 'read' the exit status of build and forward that
to the exit status of my xil-highlight program.

If you're using bash as your shell, try
build | xil-highlight ; [ ${PIPESTATUS[0]} = 0 ]

I don't believe this is portable across POSIX, and you may need to
specify the SHELL variable explicitly in the Makefile if it calls bash
in sh mode by default.

[Andrew Greensted]

Thanks all for your help.

Cheers
Andy

[Old Wolf]

On Jul 29, 9:28 am, Antoninus Twink <[e-mail]:

If you're using bash as your shell, try
build | xil-highlight ; [ ${PIPESTATUS[0]} = 0 ]

I don't believe this is portable across POSIX, and you may need to
specify the SHELL variable explicitly in the Makefile if it calls bash
in sh mode by default.

Lol, the king of wrong non-portable answers,
starts talking about portability. Post of the week.