On 3/31/2008 7:10 AM, Luuk wrote:
> Ed Morton schreef:
>
>>On 3/31/2008 6:14 AM, Luuk wrote:
>>
>>>Rajan schreef:
>>>
>>>
>>>>"Luuk" <Luuk@[EMAIL PROTECTED]
> wrote in message
>>>>news:3ve5c5-p27.ln1@[EMAIL PROTECTED]
>>>>
>>>>
>>>>>Peter schreef:
>>>>>
>>>>>
>>>>>>Hello, seems that I'm missing something obvious. There is file with
>>>>>>variable number of field, is there any simple way in awk to print
>>>>>>fields starting with field N up to the end of line. e.g.
>>>>>>
>>>>>>$ cat test.txt
>>>>>>a b c
>>>>>>a b c d
>>>>>>a b c d e f
>>>>>>a b c d v e
>>>>>>
>>>>>>How to print
>>>>>>$ awk <???> test.txt
>>>>>>
>>>>>>d
>>>>>>d e f
>>>>>>d v e
>>>>>>
>>>>>>Of course this is simplification of real data I have so I definitely
>>>>>>need awk to parse it ;) Thank you very much in advance.
>>>>>
>>>>>$ awk -v nr=4 '{ for (x=nr; x<=NF; x++) {
>>>>> printf $x " "; }; print " " }' test.txt
>>>>>
>>>>>
>>>>>--
>>>>>Luuk
>>>>
>>>>One thing that we should note here is we will lose spacing between the
>>>>fields this way.
>>>>
>>>>Rajan
>>>
>>>read again, it says:
>>>printf $x " ";
>>>
>>>so, the output is:
>>>/tmp # awk -v nr=4 '{ for (x=nr; x<=NF; x++) {
>>> > printf $x " "; }; print " " }' test.txt
>>>
>>>d
>>>d e f
>>>d v e
>>
>>Right, so if the input was tab-separated for example, you'd be changing
all the
>>tabs to blank chars.
>>
>>More im****tantly, you aren't providing the right arguments to printf so
you
>>could get radically different output than your input. Look:
>>
>>$ echo "a c d e f" | awk -v nr=4 '{ for (x=nr; x<=NF; x++) {
>> printf $x " "; }; print " " }'
>>e f
>>$ echo "a c d %s f" | awk -v nr=4 '{ for (x=nr; x<=NF; x++) {
>> printf $x " "; }; print " " }'
>>awk: cmd. line:1: (FILENAME=- FNR=1) fatal: not enough arguments to
satisfy form
>>at string
>> `%s '
>> ^ ran out for this one
>>
>>The first argument for printf is a format, not input data.
>>
>>ITYM:
>>
>>$ echo "a c d %s f" | awk -v nr=4 '{ for (x=nr; x<=NF; x++) {
>> printf "%s ",$x; }; print " " }'
>>%s f
>>
>>but that still, in addition to potentially changing all the white space,
>>adds 2 blank chars to the end of the line. To avoid that problem do
this:
>>
>>$ echo "a c d %s f" | awk -v nr=4 '{ for (x=nr; x<=NF; x++) {
>> printf "%s%s",sep,$x; sep=FS }; print "" }'
>>%s f
>>
>>Regards,
>>
>> Ed.
>>
>
>
> i agree totally...
>
> with you last suggestion you would also change all field-seperators to
> default seperators used with awk
>
Right, it was just to fix your additional-white-space problem. You can't
in
general fix the other problem with a loop (you need the sub()s solution),
though
by using FS instead of a space you may get more milage if you're parsing
files
that are separated by some specific, non-RE, FS value that isn't a single
blank
char.
Ed.
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