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awk getline function help

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# 1  
Old 04-02-2014
awk getline function help
Hello All ,

I have to split a file as well as keep the header in all the splitted files.

For this I am using the getline function of awk to keep the header however the catch is header is of 4 lines and I have to hold all the 4 lines by getline function(or is there any other option ???) into a variable .

Below is the code

Code:
awk 'BEGIN{getline f;}NR%3==2{x="F"++i;a[i]=x;print f>x;}{print > x}END{for(j=1;j<i;j++)print> a[j];}'

Currently the getline function is only holding the first line of header file and I want it to hold all the 4 lines

Below is the sample input

Code:
HEADER
HEADER
HEADER
HEADER
 Unix
 Linux
 Solaris
 ABC
 DEF
 IGH
 Unix
 Linux
 Solaris

Want the output as

First file

Code:
HEADER
HEADER
HEADER
HEADER
 Unix
 Linux
 Solaris

Second file
Code:
HEADER
HEADER
HEADER
HEADER
 ABC
 DEF
 IGH

and so on

Please suggest
# 2  
Old 04-02-2014
Code:
awk 'BEGIN{getline f1;getline f2; getline f3; getline f4; f=f1 "\n" f2 "\n" f3 "\n" f4}NR%3==2{x="F"++i;a[i]=x;print f>x;}{print > x}END{for(j=1;j<i;j++)print> a[j];}'

# 3  
Old 04-02-2014
Thanks a lot however I am getting the below error

awk: A print or getline function must have a file name.

I have blank lines in file

Please let me know how to overcome that
# 4  
Old 04-02-2014
In the BEGIN section, there no file open yet, so you can't getline unless you redirect it.
Try
Code:
awk     'NR < 5         {HD[NR]=$0; next}
         !((NR-5)%3)    {FN="F"++i; for (j=1; j<=4; j++) print HD[j] > FN}
                        {print $0 > FN}             
        ' file

This User Gave Thanks to RudiC For This Post:
Pratik4891
# 5  
Old 04-02-2014
Quote:
Originally Posted by RudiC
In the BEGIN section, there no file open yet, so you can't getline unless you redirect it.
Try
Code:
awk     'NR < 5         {HD[NR]=$0; next}
         !((NR-5)%3)    {FN="F"++i; for (j=1; j<=4; j++) print HD[j] > FN}
                        {print $0 > FN}             
        ' file

Code:
$ cat file
hdr1
hdr2
hi
hello
$ awk ' BEGIN{ getline a;getline b } { print a b $0 } ' file
hdr1hdr2hi
hdr1hdr2hello
$

This User Gave Thanks to anbu23 For This Post:
RudiC
# 6  
Old 04-02-2014
The getline is a tricky function to use and it can hold surprises. For example, if you use getline in the form getline f then this also changes the variable NR and FNR, so if you first do 4 getlines to get the header into variables or arrays, then when reading the first line after the headers, NR and FNR are equal to 5. This may, or may not be what you expect..
Last edited by Scrutinizer; 04-02-2014 at 12:03 PM..
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