how do I redirect output for set -x

[Richard Mertz]

I would like to send all the output generated by a script to a file. It appears that the output from set -x is not either stderr or stdout, so the normal 2>&1 >/tmp/abc doesn't send trace info. Anyone know how to do this?

[Ian Dennison_1]

he he he! My soapbox issue!

Theres a 3rd output stream (called Std-something). Undocumented of course.

"2>&1" does not pick it up, but "|tee -a /tmp/abc" probably will. Try it and see!

Ancient Proverb - "Give a programmer a well-defined set of standards, and they shall find a way to break them!"

Share and Enjoy! Ian

[Michael Tully]

Hi,

The easiest way is to start a typescript file.

# script /tmp/output
# run_my_script.sh

The output will go to both the screen and the /tmp/output file.

HTH
Michael

[James R. Ferguson]

Hi Richard:

#!/usr/bin/sh
set -x
date
echo hi
echo bye

Now:

./mysh 2> ./mysh.debug.debug

...directs stderr to the .debug file...

...and:

/tmp/tester 2> /tmp/tester.debug 1>&2

...directs both stderr and stdout to the .debug file.

Regards!

...JRF...

[Tony Contratto]

Hi Richard,

Not sure if this is you problem but here goes...

In your question you have:
"2>&1 >/tmp/abc"

This will NOT send stderr and stdout to the file /tmp/abc

">/tmp/abc 2>&1" WILL send both stderr and stdout to the file /tmp/abc

Order does matter.

Hope this helps...
Tony

[Richard Mertz]

More info for you guys

I already have a wrapper for my scripts. Essenentially the wrapper does:

daScript |tee -a logfile 2>&1

contents of daScript

set -x
echo abc
echo 123
echo easy as

The trace does not end up in the logfile.

[Ian Dennison_1]

All,

I have just tested the following script,...

#!/usr/bin/hs

# Comment - wrong shell is deliberate
bdf

# End Script

By running '/tmp/test1 2>&1 |tee -a /tmp/aa' picks up the error in the file /tmp/aa.

By running '/tmp/test1 |tee -a /tmp/aa 2>&1', no output is displayed in the /tmp/aa file.

Running 11.11 (64bit), Patch Dec 2001, on a N4000.

Try reversing the order of 'tee' and '2>&1' as in the first example in this posting.

Share and Enjoy! Ian

[Ian Dennison_1 · Accepted solution]

Sorry, wrong test script.

However, when I put a 'set -x' command in a simple script, the "2>&1 |tee -a /tmp/logfile" command does capture the debug output in the file.

Share and Enjoy! Ian

[James R. Ferguson]

Hi Richard:

Is this what you want?:

The wrapper:

#!/usr/bin/sh
/tmp/tester 2>&1|tee -a /tmp/tester.debug

The script (/tmp/tester):

#!/usr/bin/sh
set -x
date
echo hi
echo bye
exit 0

NOW: The output (stderr & stdout) appear both on your terminal *and* in /tmp/tester.debug:

+ date
Wed Jan 29 20:01:38 EST 2003
+ echo hi
hi
+ echo bye
bye
+ exit 0

Regards!

...JRF...

[Bill Hassell]

The reason that 2>&1 >/tmp/abc doesn't work is that redirection occurs left to right, so 2>&1 says:

send stderr to stdout as currently defined

and >/tmp/abc says: send stdout to /tmp/abc

but stderr was connected to stdout *before* it was redefined. So stderr goes to whatever stdout used to be.

The correct order is: redirect stdout, then redirect stderr to whatever stdout has become:

sh -x script_name >/tmp/abc 2>&1

I debug scripts this way by piping the stderr and stdout into more as in:

sh -x script_name 2>&1 | more

Note that -x is effective for the main body of the script and disappears inside functions. Also note that stderr (trace output) may not be perfectly shuffled into the stdout lines...shell timing issues.

[Richard Mertz]

Thanks guys!

Richard