Compare a sorted and an unsorted file

Question

I have two files that I want to compare. A sorted and an unsorted one.

ex fileA (sorted)

 ABA 
 FRE 
 DIR

ex fileB (unsorted)

 AJGHEKSLANVJJFABAKEIFJA 
 OPTOEKSMKVMGKVABAALKKSK

is there a way to find which words from fileA exist in fileB?

There are many variations of this question...it's almost boring how many they are... a quick search through my posts [returns this](http://unix.stackexchange.com/a/284679) though I'm sure you'll find plenty more if you take the time to search — don_crissti, Feb 23 '17 at 15:18
The example fileA is not sorted, at least not lexicographically. The example unsorted fileB is. Is this an error in the examples? — cherdt, Feb 23 '17 at 16:18
no I just thought sorted means that every line has only one word. In addition, in the file I have fileA is sorted alphabetically — Angelos Souleles, Feb 23 '17 at 16:38

score 0 · Answer 1 · answered Feb 23 '17 at 15:13

0

There may be tools to do it faster, but you could consume the first file in a loop and check like

while read -r pat; do
    if grep -q "$pat" fileB; then
        printf '%s has a match' "$pat"
    fi
done < fileA

answered Feb 23 '17 at 15:13

Eric Renouf

18,141
4
49
65

does this code contains any mistakes? – Angelos Souleles Feb 23 '17 at 18:20
@AngelosSouleles I guess that's a hard question to answer for sure, but for me with the sample files you gave it finds `ABA` and not either of the other 2. It will, as written, treat your words in `fileA` as patterns, not fixed strings. add `-F` to the `grep` command to fix that if you want. The `printf` also doesn't include a newline, so that could be a mistake as well – Eric Renouf Feb 23 '17 at 18:35

score 0 · Answer 2 · answered Feb 23 '17 at 15:16

0

Try this :

grep -f fileB fileA

All the lines from fileA that are there in fileB would be displayed on the console.

answered Feb 23 '17 at 15:16

ss_iwe

1,136
6
12

1

I don't think that's what the question is going for. For example, `ABA` appears in the middle of the second line, so is a word from fileA that's in fileB, but your search wouldn't report it – Eric Renouf Feb 23 '17 at 15:18
Perhaps yeah, but the question "is there a way to find which words from fileA exist in fileB?" made me think the way I answered the question. – ss_iwe Feb 23 '17 at 15:26
I would like the ABA on the second line to be reported by the search, sorry for the misunderstanding – Angelos Souleles Feb 23 '17 at 15:30
@EricRenouf Apart from the misunderstanting, the `-x` and `-w` options could tackle this problem. – FelixJN Feb 23 '17 at 16:16
@Fiximan Since the pattern can appear anywhere in a line, I don't think that `-x` or `-w` will help with this particular problem. don_cristi's answer that he linked to above has a good potential solution: `grep -oFf fileA fileB | sort -u` – Eric Renouf Feb 23 '17 at 17:19
@Fiximan non of the solutions worked. I tested them with files I knew they have some of the fileA words but I didnt get any result – Angelos Souleles Feb 23 '17 at 18:22
@AngelosSouleles @EricRenouf Not what I meant. I was talking about searching for e.g. "A" and matching only lines like "this A that", "A that" and "this A" (`-w` option, note the spaces) or lines that are "A" (and this only, `-x` option), respectively, WITHOUT matching lines like "thisAthat". But it looks like I misunderstood the requirements, when the questioner was referring to "words" that needed matching. – FelixJN Feb 24 '17 at 09:45

Compare a sorted and an unsorted file

2 Answers2