echo to stderr and tee to log file?

Question

In bash script,

echo "error" 1>&2 | tee -a log

will print stderr in screen but no log to file, how to do these at same time?

score 13 · Accepted Answer · answered Nov 13 '12 at 13:18

13

To echo the text to both the log file and stderr, but not stdout, try this:

echo "error" | tee -a log 1>&2

answered Nov 13 '12 at 13:18

ams

I'm not 100% sure what the OP wanted to do, but this is by far the best solution for my own case. I think the problem is that it's easy to think the redirection should be applied to the `echo`, but doing it to the `tee` command works perfectly, thanks! – Haravikk Jul 10 '13 at 13:14

score 8 · Answer 2 · answered Nov 13 '12 at 10:54

8

echo "error" 1>&2 | tee -a log

With the first part 1>&2, what you are saying is: "Redirect stdout to stderr". So the echoed output "error" goes to stderr.

Pipe (|) only reads from stdout, not stderr. So tee doesn't get any stdin at all from the pipe. Hence, it appends nothing to the log file.

answered Nov 13 '12 at 10:54

P.P

3

+1. Very fine answer, except for a solution: it might be worthwile to mention `2>&1` as correct for this purpose. – glglgl Nov 13 '12 at 10:58
yes, ic. But how to echo to stderr and write err log to file? – timy Nov 13 '12 at 11:41
@timy If you *redirect* stderr to stdout then you can do that: `echo "error" 2>&1 | tee -a log`. Now both stderr will also go to stdout and you can see both on the screen and will also append to the log. – P.P Nov 13 '12 at 11:49
@KingsIndian 2>&1 will output nothing to stderr, which is I want to do here. – timy Nov 13 '12 at 12:01
@timy Unless some acutal error occurs "echo"ed output will only go `stdout`. You are right that `2>&1` will write nothing to stderr. But since stdout & stderr both go to console, you don't really need to worry about that. – P.P Nov 13 '12 at 12:14

score 7 · Answer 3 · answered Nov 13 '12 at 11:32

7

To view both stdout and stderr on the console and send both streams to a log, redirect stderr to stdout as shown below:

progam.sh 2>&1 | tee -a log

answered Nov 13 '12 at 11:32

dogbane

score 0 · Answer 4 · answered Nov 13 '12 at 10:46

0

But default only stdout is passed along in pipes, so that in

$ echo "error" | tee

tee only sees the stout from the echo, not the stderr. stderr will still be displayed in the terminal.

answered Nov 13 '12 at 10:46

Benjamin Bannier

4 Answers4