pipe'd grep: grep on result of another grep

Question

Q: How do I pipe multi-results of first search to search a second file.

Ex:

1) FILE1
system abc{
system ghi{
....
...

2) FILE2
define ABC_1_SUFFIX  0XF67
define ABC_2_SUFFIX  0XF34
define DEF_1_SUFFIX  0XF65
define DEF_2_SUFFIX  0XF11
define GHI_1_SUFFIX  0XF73
define GHI_2_SUFFIX  0XF82  


grep -r "^system" file | awk '{print $2}'   
grep -r "#define.*<result of 1st grep>" file2

Task: How do I pass result of first grep (which is abc,def,ghi against grep -r "^system" ) inside second grep. I know pipe/xargs but cant figure this out yet.

I did search related topic but solution didnt work out.
1] GREP by result of awk
2] grep using grep results

Thanks in advance

Please add sample input (no descriptions, no images, no links) and your desired output for that sample input to your question (no comment). — Cyrus, Jul 07 '20 at 20:39
Are you expecting multiline output from the first grep and want to match each? It feels like you want `xargs`, but it's not really clear what you're trying to do. — William Pursell, Jul 07 '20 at 20:44
@WilliamPursell, yes .. so the second grep is like grep'ing over loop of results of first. I have not used xargs in a grep on a file, could you please let me know how I can use same. Thanks for your hints — sreekesh padmanabhan, Jul 07 '20 at 23:34
Sorry, it's still not at all clear what you want. From the sample files you've shown, it seems like the solution you are looking for is `cat FILE2`. — William Pursell, Jul 08 '20 at 15:54
@WilliamPursell I removed "system def{" from FILE1. Now, the result should be all address related to abc and ghi only, omitting def. A script will work it but trying for a one liner hack. Pls let me know. — sreekesh padmanabhan, Jul 08 '20 at 20:09

score 1 · Answer 1 · answered Jul 09 '20 at 17:13

1

It's still not really clear exactly what you want, but perhaps something like:

$ cat file1
system abc{
system ghi{
$ cat file2
define ABC_1_SUFFIX  0XF67
define ABC_2_SUFFIX  0XF34
define DEF_1_SUFFIX  0XF65
define DEF_2_SUFFIX  0XF11
define GHI_1_SUFFIX  0XF73
define GHI_2_SUFFIX  0XF82
$ awk '/^system/ && NR==FNR { gsub("[^a-zA-Z]","",$2); 
    a[toupper($2)] = 1; next } 
    /^define/ {for(k in a) if(match($0,k)) print $3}' file1 file2
0XF67
0XF34
0XF73
0XF82

answered Jul 09 '20 at 17:13

William Pursell

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Thanks, this is what I want! Appreciate it, sorry if I wasnt exaclty clear with my Q but I guess you have the answer neverthless :) – sreekesh padmanabhan Jul 09 '20 at 21:02
It's probably easier to preproces file1 into a file of patterns to match and use 'grep -i -f ...' – William Pursell Jul 10 '20 at 11:47

ΔO 'delta zero' · Answer 2 · 2020-07-08T12:32:11.867

0

Do you mean passing the first command's output to the second command itself?

Maybe something like this?

fisrt="$(grep -r "^system" file)"
second="$(grep -r "#define.*${first}" file2)"

Ugly one-liner:

grep -r "#define.*$(grep -r "^system" file)" file2

edited Jul 08 '20 at 12:32

answered Jul 07 '20 at 20:41

ΔO 'delta zero'

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Thx for the edit, @William Pursell, that's what I meant – ΔO 'delta zero' Jul 07 '20 at 20:50
grep -ri "#define.*grep -r '^system.*{' FILE1| awk '{print $2}'" FILE2 didnt work for the above files – sreekesh padmanabhan Jul 07 '20 at 23:39

pipe'd grep: grep on result of another grep

2 Answers2