Using process substitution, only send stderr to process

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0
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I have this:

exec > >( while read line; do echo " stdout: $line"; done )
exec 2> >( while read line; do echo " stderr: $line"; done )

echo "rolo"
>&2 echo "cholo"

if you run that script, it results in the following output:

stdout: rolo

stdout: stderr: cholo

how can I only send stderr to the second process substitution line?
I don't get it.

I don't understand why this is happening:

stdout: rolo

stdout: stderr: cholo # what lol

edited May 8 at 4:55

asked May 8 at 4:48

Alexander Mills

1,885929

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up vote
0
down vote

favorite

I have this:

exec > >( while read line; do echo " stdout: $line"; done )
exec 2> >( while read line; do echo " stderr: $line"; done )

echo "rolo"
>&2 echo "cholo"

if you run that script, it results in the following output:

stdout: rolo

stdout: stderr: cholo

how can I only send stderr to the second process substitution line?
I don't get it.

I don't understand why this is happening:

stdout: rolo

stdout: stderr: cholo # what lol

edited May 8 at 4:55

asked May 8 at 4:48

Alexander Mills

1,885929

add a commentÂ |Â

up vote
0
down vote

favorite

I have this:

exec > >( while read line; do echo " stdout: $line"; done )
exec 2> >( while read line; do echo " stderr: $line"; done )

echo "rolo"
>&2 echo "cholo"

if you run that script, it results in the following output:

stdout: rolo

stdout: stderr: cholo

how can I only send stderr to the second process substitution line?
I don't get it.

I don't understand why this is happening:

stdout: rolo

stdout: stderr: cholo # what lol

edited May 8 at 4:55

asked May 8 at 4:48

Alexander Mills

1,885929

I have this:

exec > >( while read line; do echo " stdout: $line"; done )
exec 2> >( while read line; do echo " stderr: $line"; done )

echo "rolo"
>&2 echo "cholo"

if you run that script, it results in the following output:

stdout: rolo

stdout: stderr: cholo

how can I only send stderr to the second process substitution line?
I don't get it.

I don't understand why this is happening:

stdout: rolo

stdout: stderr: cholo # what lol

edited May 8 at 4:55

asked May 8 at 4:48

Alexander Mills

1,885929

edited May 8 at 4:55

asked May 8 at 4:48

Alexander Mills

1,885929

asked May 8 at 4:48

Alexander Mills

1,885929

asked May 8 at 4:48

Alexander Mills

1,885929

add a commentÂ |Â

1 Answer
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3
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You set up the redirections in the wrong order. The standard output of the second process substitution (which prefixes with stderr:) has its standard output prefixed by the first process substitution, because it was run afterwards.

Try this instead:

exec 2> >( while read line; do echo " stderr: $line"; done )
exec > >( while read line; do echo " stdout: $line"; done )

echo "rolo"
echo "cholo" >&2

This outputs

 stderr: cholo
 stdout: rolo

which is what I presume you want.

answered May 8 at 5:06

Kusalananda

102k13199315

Comments are not for extended discussion; this conversation has been moved to chat.
â€“Â terdonâ™¦
May 8 at 16:37

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1 Answer
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active

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1 Answer
1

active

oldest

votes

up vote
3
down vote

accepted

Try this instead:

exec 2> >( while read line; do echo " stderr: $line"; done )
exec > >( while read line; do echo " stdout: $line"; done )

echo "rolo"
echo "cholo" >&2

This outputs

 stderr: cholo
 stdout: rolo

which is what I presume you want.

answered May 8 at 5:06

Kusalananda

102k13199315

Comments are not for extended discussion; this conversation has been moved to chat.
â€“Â terdonâ™¦
May 8 at 16:37

add a commentÂ |Â

up vote
3
down vote

accepted

Try this instead:

exec 2> >( while read line; do echo " stderr: $line"; done )
exec > >( while read line; do echo " stdout: $line"; done )

echo "rolo"
echo "cholo" >&2

This outputs

 stderr: cholo
 stdout: rolo

which is what I presume you want.

answered May 8 at 5:06

Kusalananda

102k13199315

Comments are not for extended discussion; this conversation has been moved to chat.
â€“Â terdonâ™¦
May 8 at 16:37

add a commentÂ |Â

up vote
3
down vote

accepted

Try this instead:

exec 2> >( while read line; do echo " stderr: $line"; done )
exec > >( while read line; do echo " stdout: $line"; done )

echo "rolo"
echo "cholo" >&2

This outputs

 stderr: cholo
 stdout: rolo

which is what I presume you want.

answered May 8 at 5:06

Kusalananda

102k13199315

Try this instead:

exec 2> >( while read line; do echo " stderr: $line"; done )
exec > >( while read line; do echo " stdout: $line"; done )

echo "rolo"
echo "cholo" >&2

This outputs

 stderr: cholo
 stdout: rolo

which is what I presume you want.

answered May 8 at 5:06

Kusalananda

102k13199315

answered May 8 at 5:06

Kusalananda

102k13199315

answered May 8 at 5:06

Kusalananda

102k13199315

answered May 8 at 5:06

Kusalananda

102k13199315

Comments are not for extended discussion; this conversation has been moved to chat.
â€“Â terdonâ™¦
May 8 at 16:37

add a commentÂ |Â

Comments are not for extended discussion; this conversation has been moved to chat.
â€“Â terdonâ™¦
May 8 at 16:37

Comments are not for extended discussion; this conversation has been moved to chat.
â€“Â terdonâ™¦
May 8 at 16:37

add a commentÂ |Â

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