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fgrep command

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# 1  
Old 12-23-2009
fgrep command
How can we use fgrep command to search pattern on perticular field on a file.
eg : I have a parren file having format
cat patternfile
SPA16S199982
SPA5S26330

I want to seach these pattern on FIRST field of File2(since other field has
same data) and that too maching entirely.

cat File2
SPA16S199982P|Diamond Necklace|SPA16S199982|1
SPA16S199982|Diamond Necklace|SPA16S199982|1
SPA5S26330|Diamond Necklace|SPA16S199982|1


Desired O/p
----------
SPA16S199982|Diamond Necklace|SPA16S199982|1
SPA5S26330|Diamond Necklace|SPA16S199982|1

The command that i am using is fgrep -f -x patternfile File2. How to modify this command for grepping on first column.


Thanxx in advance
# 2  
Old 12-23-2009
if using fgrep is not a compulsion:

Code:
while read LINE;do grep -w "^$LINE" File2;done < patternfile

or with awk this should also work

Code:
awk -F"|" 'BEGIN{while(getline<"patternfile") arr[$1]=1 } ; arr[$1] ==1 {print $0 } ' File2

Last edited by clx; 12-23-2009 at 03:47 AM.. Reason: added awk soln
# 3  
Old 12-23-2009
You can not use fgrep for this purpose, you have to use grep. Also you can not use the -x option since that matches the whole line, plus you can not use the pattern unmodified. So you either have to modify the pattern file or modify the patterns on the fly:
Code:
grep -wf <(sed s'/^/^/' patternfile) File2

or use awk:
Code:
awk -F '|' 'NR==FNR{A[$1]=1;next}A[$1]' patternfile File2

Last edited by Scrutinizer; 12-25-2009 at 01:40 PM..
# 4  
Old 12-23-2009
did you mean word match ?

Code:
13:17:45 : tmp :cat pat
SPA16S199982
SPA5S26330
13:17:46 : tmp :fgrep -w -f pat example
SPA16S199982P|Diamond Necklace|SPA16S199982|1
SPA16S199982|Diamond Necklace|SPA16S199982|1
SPA5S26330|Diamond Necklace|SPA16S199982|1

Or if you wanted only the first field to match, then give ^ at the pattern as

Code:
$ cat pat
^SPA16S199982
^SPA5S26330

$ grep -w -f pat example
SPA16S199982|Diamond Necklace|SPA16S199982|1
SPA5S26330|Diamond Necklace|SPA16S199982|1

# 5  
Old 12-23-2009
Hi All, the awk command is working fine Thanks a lot .Now the major think is my pattern file and main file has 5million data. In that case will the awk command be faster ?
# 6  
Old 12-23-2009
If the awk command can handle the 5M records I think it will be plenty fast.
# 7  
Old 12-23-2009
Code:
#!/bin/sh

PATTERNS=`cat patternfile`

for pat in $PATTERNS
do
    cat File2 | grep "^$pat\>"
done

Last edited by pludi; 12-23-2009 at 09:19 AM.. Reason: code tags, please...
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