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Retreive the records from file2 by using the first field in file1

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# 1  
Old 10-18-2012
Data Retreive the records from file2 by using the first field in file1
Hi Freinds,

i have a file1 as below
file1
Code:
 
1|ndmf|fdd|d3484|34874
2|jdehf|wru7|478|w489
3|dfkj|wej|484|49894

file2 contains lakhs of records and not in sorted order
i want to retrive only the records from file2 by searcing the first field of file 1

i used

Code:
 
grep ^1 file2 >out.txt
grep ^2 file2 >>out.txt
grep ^3 file2>>out.txt

this i need to do 3 times . if i have some 1L records in file1 and need to take only matching records , i am struck

Please help me i am newbie to shell
# 2  
Old 10-18-2012
Try..

Code:
IFS="|"
while read x y
do
grep "^$x" file2 >> out.txt
done<file

This User Gave Thanks to pamu For This Post:
i150371485
# 3  
Old 10-18-2012
Assuming that file2 is also a pipe-separated file and you wish to match the first fields of the 2 files (i.e., 1 will match only 1 and not 12,132,etc.), try:
Code:
awk 'FNR==NR{a[$1];next}$1 in a' FS=\| file1 file2 > out.txt

@pamu
You don't need to open out.txt multiple times in the loop. Just keep it open for the duration of the loop. That'll be more efficient.
Code:
while IFS='|' read x y
do
grep "^$x|" file2
done < file1 > out.txt

This User Gave Thanks to elixir_sinari For This Post:
i150371485
# 4  
Old 10-18-2012
Better than running grep 1L times is to prepare a "pattern file" and use grep with it:
Code:
awk -F"\|" '{print $1}' file1 > pattfile; grep -f pattfile file2 >out.txt; rm pattfile

This User Gave Thanks to RudiC For This Post:
i150371485
# 5  
Old 10-18-2012
@pamu.Elixir,Rudic : Thaks for you reply and help. Appreciate your help Smilie it is working as expected Smilie
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