How to find matching patterns from two different files - regex

Question

I have these two files, and would like to find the matching patterns
for the second file based on the entries from the first file, then print out the
matched results.
Here is the first file,
switch1 Ethernet2 4 4 5
switch1 Ethernet4 4 4 5
switch1 Ethernet7 4 4 5
switch1 Ethernet9 4 4 5
switch1 Ethernet10 4 4 5
switch1 Ethernet13 1 4 5
switch1 Ethernet14 1 4 5
switch1 Ethernet15 1 4 5
switch2 Ethernet5 4 4 5
switch2 Ethernet6 1 4 5
switch2 Ethernet7 4 5
switch2 Ethernet8 1 4 5
switch1 Ethernet1 2002 2697 2523
switch1 Ethernet17 2002 2576 2515
switch1 Ethernet11 2002 2621 2617
switch2 Ethernet1 2001 2512 2577
And here is the second file,
switch1 Ethernet1 1 4 5 40 2002 2523 2590 2621 2656 2661 2665 2684 2697 2999
switch1 Ethernet2 1 4 5 40 2002 2504 2505 2508 2514 2516 2517 2531 2533 2535 2544 2545 2547 2549 2555 2566 2571 2575 2589 2590 2597 2604 2611 2626 2629 2649 2666 2672 2684 2691 2695
switch1 Ethernet3 40
switch1 Ethernet4 1 4 5 40 2002 2504 2516 2517 2535 2547 2549 2571 2579 2590 2597 2604 2605 2620 2624 2629 2649 2684 2695
switch1 Ethernet5 1 4 5 40 55 56 2000 2002 2010 2037 2128 2401 2409 2504 2526 2531 2540 2541 2548 2562 2575 2578 2579 2588 2590 2597 2604 2606 2608 2612 2615 2616 2621 2638 2640 2645 2650 2666 2667 2669 2670 2674 2678 2684 2690 2696
switch1 Ethernet6 40
switch1 Ethernet7 1 4 5 40 2037 2128 2174 2401 2409 2463 2526 2535 2540 2541 2544 2562 2578 2579 2590 2616 2621 2625 2631 2645 2659 2667 2670 2674 2678 2682 2684 2690 2696
switch1 Ethernet8 1 4 5 40 2037 2128 2396 2401 2409 2420 2531 2619 2640 2653 2658 2669 2677 2683 2684
switch1 Ethernet9 1 4 5 40 2128 2169 2396 2401 2409 2420 2504 2515 2531 2553 2578 2597 2619 2621 2640 2658 2669 2677 2683 2684 2694
switch1 Ethernet10 1 4 5 40 2079 2128 2169 2378 2396 2453 2509 2578 2591 2597 2621 2634 2641 2657
switch1 Ethernet11 1 4 5 40 2002 2128 2169 2396 2453 2509 2512 2520 2526 2549 2552 2564 2571 2575 2589 2591 2597 2611 2617 2621 2634 2641 2657 2671 2676 2686 2694
switch1 Ethernet12 1 4 5 40 2079 2378 2396 2453 2515 2531 2553 2597 2619 2621 2640 2657 2669 2677 2684 2694
switch1 Ethernet13 1 4 5 40 2174 2396 2453 2463 2508 2524 2531 2536 2546 2567 2597 2629 2640 2657 2669 2674 2684
switch1 Ethernet14 1 4 5 40 2524 2536 2544 2567 2575 2582 2628 2640 2659 2674 2681 2689
switch1 Ethernet15 1 4 5 40 2515 2553 2575 2582 2621 2628 2640 2681 2689 2694
switch1 Ethernet16 1 4 5 40 2513 2539 2544 2553 2561 2573 2575 2582 2619 2640 2670 2681
switch1 Ethernet17 1 4 5 40 2002 2508 2513 2515 2531 2538 2539 2544 2547 2553 2561 2570 2573 2575 2576 2582 2586 2601 2608 2619 2621 2640 2658 2670 2681
the results should display,
switch1 Ethernet13 1 4 5
switch1 Ethernet14 1 4 5
switch1 Ethernet15 1 4 5
switch1 Ethernet8 1 4 5
switch1 Ethernet16 1 4 5
switch1 Ethernet1 2002 2697 2523
switch1 Ethernet17 2002 2576 2515
The challenging part for me is that I don't know
how to compare a pattern from one line of the first file to all the lines of the second file. And in this case, it has 5 patterns to match, when the second file doesn't have
consistent fields to work with. Some lines are shorter than the others, and the matching fields may not be the same with other lines.
Any idea or suggestion would be greatly appreciated.
Thanks much in advance.

Answer 1

Something like this should work, but there's probably a better way
#!/bin/bash
patternfile='file1'
exec 4<$patternfile
otherfile='file2'
while read -u4 pattern; do
grep ".*`echo ""$pattern"" | sed 's/\s\+/ \\\+.* /g'`.*" $otherfile
done
P.S. This doesn't output all of the lines you said you wanted:
Ethernet8 is switch2 in one and switch1 in the other. fixing that in regex would be really ugly, but you could use awk to get only the records you want.
Ethernet16 isn't even in the first file, I think that line is a mistake.
Ethernet1 and Ethernet17 have the records out of order, which my solution can't deal with.