ash - exit code for a piped process

[Alexander Kriegisch]

I would like to determine the exit code of 'foo' in
foo | bar

I bash there is the PIPESTATUS array, but in ash (which I must use)
there is no such thing as PIPESTATUS or arrays. Is there any canonical
way or at least a workaround to achieve both piping the foo's output
into bar unconditionally *and* determining foo's exit code?

Thanks

[Loïc Grenié]

Post by Alexander Kriegisch
I would like to determine the exit code of 'foo' in
foo | bar
I bash there is the PIPESTATUS array, but in ash (which I must use)
there is no such thing as PIPESTATUS or arrays. Is there any canonical
way or at least a workaround to achieve both piping the foo's output
into bar unconditionally *and* determining foo's exit code?

x=`((( foo 3>&- 4>&- ); echo $? >&3)| bar >&4 3>&- 4>&-) 3>&1` 4>&1

should do the trick. The exit code of foo is in x, the output of bar
goes to the output of the command.

Hope this helps.

Lo?c

[Alexander Kriegisch]

Post by Loïc Grenié
x=`((( foo 3>&- 4>&- ); echo $? >&3)| bar >&4 3>&- 4>&-) 3>&1` 4>&1

Thanks, Lo?c. I will consider your solution if I ever have a case like
this again, but my current workaround is rather simple to read and uses
a text buffer for the first command's output. I can do this because I
know that foo's output has a limited size which can be easily handled in
memory. So I choose this way for the sake of readability:

output=$(foo)
result=$?
echo "$output" | bar

I know the solution is somewhat limited, but a feasibly workaround in my
special case. Yours is more refined and really uses pipes.
--
Alexander Kriegisch

[Tito]

Post by Loïc Grenié

Post by Alexander Kriegisch
I would like to determine the exit code of 'foo' in
foo | bar
I bash there is the PIPESTATUS array, but in ash (which I must use)
there is no such thing as PIPESTATUS or arrays. Is there any canonical
way or at least a workaround to achieve both piping the foo's output
into bar unconditionally *and* determining foo's exit code?

x=`((( foo 3>&- 4>&- ); echo $? >&3)| bar >&4 3>&- 4>&-) 3>&1` 4>&1
should do the trick. The exit code of foo is in x, the output of bar
goes to the output of the command.
Hope this helps.
Lo?c

foo > out.file
ret=$?
cat out.file | bar
# rm out.file

Untested. Just an idea...........

Ciao,
Tito

[Alexander Kriegisch]

Post by Loïc Grenié
x=`((( foo 3>&- 4>&- ); echo $? >&3)| bar >&4 3>&- 4>&-) 3>&1` 4>&1

Thanks, Lo?c. I will consider your solution if I ever have a case like
this again, but my current workaround is rather simple to read and uses
a text buffer for the first command's output. I can do this because I
know that foo's output has a limited size which can be easily handled in
memory. So I choose this way for the sake of readability:

output=$(foo)
result=$?
echo "$output" | bar

I know the solution is somewhat limited, but a feasibly workaround in my
special case. Yours is more refined and really uses pipes.
--
Alexander Kriegisch

[Tito]

Post by Loïc Grenié

Post by Alexander Kriegisch
I would like to determine the exit code of 'foo' in
foo | bar
I bash there is the PIPESTATUS array, but in ash (which I must use)
there is no such thing as PIPESTATUS or arrays. Is there any canonical
way or at least a workaround to achieve both piping the foo's output
into bar unconditionally *and* determining foo's exit code?

x=`((( foo 3>&- 4>&- ); echo $? >&3)| bar >&4 3>&- 4>&-) 3>&1` 4>&1
should do the trick. The exit code of foo is in x, the output of bar
goes to the output of the command.
Hope this helps.
Lo?c

foo > out.file
ret=$?
cat out.file | bar
# rm out.file

Untested. Just an idea...........

Ciao,
Tito

[Alexander Kriegisch]

I would like to determine the exit code of 'foo' in
foo | bar

I bash there is the PIPESTATUS array, but in ash (which I must use)
there is no such thing as PIPESTATUS or arrays. Is there any canonical
way or at least a workaround to achieve both piping the foo's output
into bar unconditionally *and* determining foo's exit code?

Thanks

[Loïc Grenié]

Post by Alexander Kriegisch
I would like to determine the exit code of 'foo' in
foo | bar
I bash there is the PIPESTATUS array, but in ash (which I must use)
there is no such thing as PIPESTATUS or arrays. Is there any canonical
way or at least a workaround to achieve both piping the foo's output
into bar unconditionally *and* determining foo's exit code?

x=`((( foo 3>&- 4>&- ); echo $? >&3)| bar >&4 3>&- 4>&-) 3>&1` 4>&1

should do the trick. The exit code of foo is in x, the output of bar
goes to the output of the command.

Hope this helps.

Lo?c