select multiple patterns with grep

Question

I have file that looks like that:

t corresponds to header of each block.

I would like to extract multiple patterns from the file and output transactions that contain required patterns altogether.

I tried the following code:

ps | grep -e 't\|u 0 1 2' file.txt

and it works well to extract header and pattern 'u 0 1 2'. However, when I add one more pattern, the output list only headers start with t #. My modified code looks like that:

ps | grep -e 't\|u 0 1 2 && u 0 2 2' file.txt

I tried sed and awk solutions, but they do not work for me as well.

Thank you for your help! Olha

Why did you use && instead of \| like when you added the second pattern? — Barmar
– Barmar, Commented Aug 13, 2020 at 21:11

Barmar · Accepted Answer · 2020-08-13 21:17:54Z

1

Use | as the separator before the third alternative, just like the second alternative.

grep -E 't|u 0 1 2|u 0 2 2' file.txt

Also, it doesn't make sense to specify a filename and also pipe ps to grep. If you provide filename arguments, it doesn't read from the pipe (unless you use - as a filename).

answered Aug 13, 2020 at 21:17

Barmar

789k57 gold badges555 silver badges669 bronze badges

Sign up to request clarification or add additional context in comments.

2 Comments

Olha Kholod Over a year ago

So, this give me both options, t # 3-436, u 0 1 2, u 0 2 2 and t # 3-437, u 0 1 2. How can I keep exact match (meaning t # 3-436, u 0 1 2, u 0 2 2 only)?

Barmar Over a year ago

You mean you only want the t # line if there were u lines matched in that block? I don't think you can do that with grep, you need something programmable like awk.

kojiro · Accepted Answer · 2020-08-13 21:14:15Z

1

You can use grep with multiple -e expressions to grep for more than one thing at a time:

$ printf '%d\n' {0..10} | grep -e '0' -e '5'
0
5
10

answered Aug 13, 2020 at 21:14

kojiro

77.8k20 gold badges151 silver badges217 bronze badges

Comments

l0b0 · Accepted Answer · 2020-08-13 21:54:14Z

0

Expanding on @kojiro's answer, you'll want to use an array to collect arguments:

mapfile -t lines < file.txt
for line in "${lines[@]}"
do
    arguments+=(-e "$line")
done

grep "${arguments[@]}"

You'll probably need a condition within the loop to check whether the line is one you want to search for, but that's it.

answered Aug 13, 2020 at 21:54

l0b0

59.6k32 gold badges155 silver badges247 bronze badges

Collectives™ on Stack Overflow

select multiple patterns with grep

3 Answers 3

2 Comments

Comments

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

3 Answers 3

2 Comments

Comments

Comments

Your Answer

Sign up or log in

Post as a guest

Related