Shell Programming and Scripting

I have two files, gmrd.txt and core_extract.txt

I need awk to look at the first column of each file and if a field appears in core_extract that also appears in gmrd.txt then it should write append that line to a file

here is what i have so far...currently it replaces the line found with "TEST"

any help appreciated

awk '
BEGIN {
FS = OFS = ";"
while (getline < "core_extract.txt" > 0)
arr[$1] = 1
}
$1 in arr {
$0 = "TEST"
}
{print}
' gmrd.txt

i'm using the K-shell on an AIX system

cheers

Code:

awk '
  BEGIN {                                        
     FS = OFS = ";"   
  }

  FNR==NR { arr[$1]=$0; next }
  1
  $1 in arr { print arr[$1] }
  ' gmrd.txt core_extract.txt

thanks for the vg!

however when I run that script it actually still leaves the output from core_extract.txt in the output - is there any way of just seeing the relevant records from gmrd.txt?

again many thanks!

from the original posting:
NOW I think you want this:

Code:

awk '
  BEGIN {                                        
     FS = OFS = ";"   
  }

  FNR==NR { arr[$1]=$0; next }
  $1 in arr { print arr[$1] }
  ' gmrd.txt core_extract.txt

vg thanks for the assitance with this - it works great!

just to get to grips with this - i'm assuming the 1 is a command that appends output to the specified file?

1 - is awk's shortcut of saying "true". When awk 'condition' [logically] evaluates to true it simply prints the current record. In your case it will print record/line from core_extract.txt.

The more explicit/equivalent way to do this would be:

Code:

{print $0}

vg, if i could tap your knowledge one more time...

how would I modify the above script to use the 4 field in gmrd.txt and the 1st field in core_extract.txt?