stupid newbie: how to write to standard error?

Hello? is there a way to pipe error message to stderr?

My script is often used this way: $awk -f script.awk < infile > outfile
so there is no chance for the user see error message. There must be a
way to write some message to stderr?

Zhang Weiwu wrote:
> Hello? is there a way to pipe error message to stderr?
>
> My script is often used this way: $awk -f script.awk < infile >
outfile
> so there is no chance for the user see error message. There must be a

> way to write some message to stderr?

Under unix:
print  >"/dev/tty"
Under messydos:
print >"/dev/stderr"



Incidentally, instead of:
awk -f script.awk < infile > outfile
simply say
awk -f script.awk infile > outfile

>
>Zhang Weiwu wrote: 
> 

In article <1104912758.831505.259670@z14g2000cwz.googlegroups.com>,
William James <w_a_x_man@yahoo.com> wrote:
>Under unix:
>print  >"/dev/tty"
>Under messydos:
>print >"/dev/stderr"

Not quite.

If you don't care about DOS and you want absolute portability:

print "message" | "cat 1>&2"

If you're using gawk, mawk, or the Bell Labs awk, any OS:

print "message" > "/dev/stderr"

Printing to /dev/tty is incorrect in the case that awk's stderr
has also been redirected, e.g.,

awk -f infile > outfile 2> errfile

HTH.

Arnold
--
Aharon (Arnold) Robbins --- Pioneer Consulting Ltd.	arnold AT skeeve DOT com
P.O. Box 354		Home Phone: +972  8 979-0381	Fax: +1 206 350 8765
Nof Ayalon		Cell Phone: +972 50  729-7545
D.N. Shimshon 99785	ISRAEL

William James wrote:

> Zhang Weiwu wrote:
> 
>
> outfile
> 
>
> 
>
>
> Under unix:
> print  >"/dev/tty"
> Under messydos:
> print >"/dev/stderr"
>

See Aharons reply.

>
> Incidentally, instead of:
> awk -f script.awk < infile > outfile
> simply say
> awk -f script.awk infile > outfile
>

Though I've never needed it myself, there are good reasons to use
"awk ... < infile" rather than "awk ... infile".

The former protects you against file names with characters that awk
wouldn't like to come across in an argument (e.g. an "=" sign). It also
has the shell open the file rather than awk, so if the file can't be
opened, you get the same error message regardless of whether you're
using awk or some other command on that file, and awk won't even be run
(not a huge deal!). The downside is that you lose the automatic setting
of FILENAME or ARGV[1].

So far it hasn't been worth the tradeoff in my environment, but others
have different needs.

Ed.

>
>Zhang Weiwu wrote: 
> 

In article <1104912758.831505.259670@z14g2000cwz.googlegroups.com>,
William James <w_a_x_man@yahoo.com> wrote:
>Under unix:
>print  >"/dev/tty"
>Under messydos:
>print >"/dev/stderr"

Not quite.

If you don't care about DOS and you want absolute portability:

print "message" | "cat 1>&2"

If you're using gawk, mawk, or the Bell Labs awk, any OS:

print "message" > "/dev/stderr"

Printing to /dev/tty is incorrect in the case that awk's stderr
has also been redirected, e.g.,

awk -f infile > outfile 2> errfile

HTH.

Arnold
--
Aharon (Arnold) Robbins --- Pioneer Consulting Ltd.	arnold AT skeeve DOT com
P.O. Box 354		Home Phone: +972  8 979-0381	Fax: +1 206 350 8765
Nof Ayalon		Cell Phone: +972 50  729-7545
D.N. Shimshon 99785	ISRAEL