grep multiline shell variable from output of executable file

Question

I'm trying to grep lines from a execution output with a multi-line shell variable, but I'm not quite sure how to do it for example, if I execute a file named run and the result is:

blahblah aaa
blahblah bbb
blabhblasd ccc
----------- ddd
...

blah blah  ggg

and so on. And then, I have a shell variable, which is a another result from grep (and is multiline), for example $VAR holds

aaa
bbb
ggg

I want to grep this $VAR from the result of run, so I have the result

blahblah aaa
blahblah bbb
blah blah  ggg

I tried something like

run | grep "VAR" but I'm not quite getting the result I want. Is there any way to grep multi-line variable from a execution output?

Answer 1

$ cat file
blahblah aaa
blahblah bbb
blabhblasd ccc
----------- ddd
...

blah blah  ggg

$ echo "$var"
aaa
bbb
ggg

$ cat file | awk -v var="$var" 'BEGIN{split(var,tmp); for (i in tmp) arr[tmp[i]]} $NF in arr'
blahblah aaa
blahblah bbb
blah blah  ggg

Replace cat file with run.

Answer 2

Does this do what you want?

run | grep -f <(printf '%s\n' "$var")

• It prints any line of the run output that matches any line in the $var variable.
• See Process Substitution in the Bash Reference Manual for an explanation of <(printf '%s\n' "$var").
• See the accepted, and excellent, answer to Why is printf better than echo? for an explanation of why I used printf instead of echo to output the contents of $var.
• See Correct Bash and shell script variable capitalization for an explanation of why I used $var instead of $VAR.