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[bash] Reading two files and change a specific field

 
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# 1  
Old 05-12-2012
[bash] Reading two files and change a specific field
Hi all.

I have 2 files like these:

file1
Code:
3    -2    5    4    .    .    .
 3    3    3    4    .    .    .
 2    2    3    4    .    .    .
3    -2    8    4    .    .    .

file2
Code:
0.4242    2    3    4    .    .    .
 2.562    7    3    4    .    .    .
 0.7242    5    5    4    .    .    .
1.1242    -2    3    4    .    .    .

and I need to read every lines from file1, cheking if ($1==3 && $2==-2) and modifying $3 to 77 in the corresponding line in file2.

The result should be:

Outputfile
Code:
 0.4242    2    77    4    .    .    .
  2.562    7    3    4    .    .    .
  0.7242    5    5    4    .    .    .
 1.1242    -2    77   4    .    .    .

I am trying in bash with:

Code:
awk ' FS ="\t" ;{ if ($1==3 && $2==-2) {getline < "file2" ; $3=77; print $0} else {getline < "file2" ; print $0}  }' file1

but there is a problem with the field separator. It seems like '\t' is not applied. Smilie

Any suggestion?

Maybe is it simplier in python?

Thank you in advance!
# 2  
Old 05-12-2012
If you apply \t to FS on the first line, then it will not work for that line. You should set FS before you start rading records. Also the way it is used:
Code:
FS ="\t"

This means that each record of file1 will get printed. Try something yo set the field separator like this:
Code:
awk -F '\t' '{ if ($1==3 && $2==-2) {getline < "file2" ; $3=77; print $0} else {getline < "file2" ; print $0}  }' file1

# 3  
Old 05-12-2012
Same problem! When the condition is satisfied, it prints the line with ' ' as a field separator, not '\t'. Smilie(
# 4  
Old 05-12-2012
Then you need to set the output field separator as well
Code:
awk 'BEGIN{ FS=OFS="\t" } {if ....

 
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