Re: [bug-gawk] problem on Using getline from a Coprocess

[夏凯]

i know it, thanks.

On Sat, Nov 12, 2011 at 22:18, John Haque <address@hidden> wrote:
> Hi.
>
> The answer can be found in the documentation that comes with gawk.
> Please read the section two-way I/O; If 'info gawk' does not work
> for you, you can produce the documentation in other formats using
> gawk.texi in the doc subdirectory of the source distribution.
>
> You need to explicitely close the pipe or the write end
> of the two-way process.
>
> On Wed, Nov 09, 2011 at 09:55:03PM +0800:
>> i want to try "Using getline from a Coprocess" but i got a error,
>> 21:37:43#tp#~> cat a.awk
>> #!/usr/bin/awk
>> {print $0 | "base64"
>> }
>
> This works because gawk closes the pipe for you when it exits. Try
> these two versions and see the difference:
>
> {
>        print $0 | "base64"
>        close("base64")
>        print "gawk"
> }
>
> vs.
>
> {
>        print $0 | "base64"
>        print "gawk"
> }
>
>
>> 21:37:47#tp#~> cat b.awk
>> #!/usr/bin/awk
>> {print $0 |& "base64"
>> "base64"|&getline a
>> print a}
>
> You need to tell "base64" that no more input is coming:
>
> {print $0 |& "base64"
> close("base64", "to")   # closes the write end
> "base64"|& getline a
> print a}
>
>
> Thanks,
>
> John
>
>> 21:37:51#tp#~> echo abc|awk -f a.awk
>> YWJjCg==
>> 21:37:55#tp#~> awk --version|head -n2
>> GNU Awk 3.1.6
>> Copyright (C) 1989, 1991-2007 Free Software Foundation.
>> 21:38:07#tp#~> echo abc|awk -f b.awk
>> ^C       #here it won't stop, so i have to use CTRL+C to stop it.
>> 21:38:16#tp#~>
>> any help is appreciated.
>> --
>> contact me:
>> MSN: address@hidden
>> GTALK: address@hidden
>



-- 
contact me:
MSN: address@hidden
GTALK: address@hidden