Get output on screen from linux command

Question

I tried to get command output in a command but I could't get it. If I run manually, It return normal result in screen.

[root@mymachine ~]# dnsdist -e "topQueries()" 1 Rest 0 100.0%

I tried with dnsdist -e 'topQueries() 2>&1 1> /tmp/abc. But /tmp/abc still was empty. I don't think screen command can resolve it. Does anyone have any recommendations?

Addition information:

1 Rest 0 100.0%

is the result from topQueries(). '-e' mean execute a command in dnsdist. It works look like we access mysql then we call a sql statement.

Yes. As my example, After I run command manually, I see this result in screen. — Thao Nguyen
– Thao Nguyen, Commented Dec 4, 2016 at 15:13
Order of redirection is important, how about examplecommand > /tmp/abc 2>&1 — rkosegi
– rkosegi, Commented Dec 4, 2016 at 15:17
If you want it, i will send. This command come from dnsdist rpm (version 1.1 beta). Command: dnsdist -e 'makeKey()' — Thao Nguyen
– Thao Nguyen, Commented Dec 4, 2016 at 15:18

Community · Accepted Answer · 2017-05-23 12:13:49Z

1

As rkosegi commented, order is important. When you run:

examplecommand 2>&1 1> /tmp/abc

It takes the stderr output and sends it to where stdout is currently going and then sends stdout to the file.

You may want, instead:

examplecommand 1> /tmp/abc 2>&1

which sends stdout to the file, then sends stderr to where stdout is currently going, namely the file.

edited May 23, 2017 at 12:13

CommunityBot

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answered Dec 4, 2016 at 15:21

Jeff Schaller

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3 Comments

Thao Nguyen Over a year ago

It's not work :( Both /tmp/abc and screen still empty value.

Thao Nguyen Over a year ago

Seem I could not get this result from both stdout and stderr

giusti Over a year ago

You just missed a > there.

V. Michel · Accepted Answer · 2016-12-04 19:01:15Z

0

To have stderr and stdout both to te screen and in a file /tmp/abc you can use tee.

$cat a.sh
echo "stderr" >&2
echo "stdout"

./a.sh 2>&1 | tee /tmp/abc
stderr
stdout

$ cat /tmp/abc
stderr
stdout

answered Dec 4, 2016 at 19:01

V. Michel

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