Tool for launching command on files with same date - bash

Question

I have several set of files (several hundreds). In each set, each file is related to a date (year/month/day) that is encoded in the file name. I want to execute a command that takes in input a file from each set for a particular date.
Since files are sometime missing in some sets, I want to only launch the command when all sets contain a file for a particular date.
I would to know if there is any existing (command line or other) tool that can do this kind of thing. I searched but I could not find anything.
The use of date as key for files is not mandatory. I guess that any tool that is generic enough will provide a way to specify the key as a parameter.
Edit:
There are less than 10 sets but each contain several hundreds of files.
Each set is located in a separate directory.

Answer 1

Since this answer is tagged with bash, here is a bash script to check if a file exists containing some date string (provided as the first argument of the script) in each of the given sets. If it exists in every one, then some_command is executed:
#!/bin/bash
datestr=$1
all_exist=Y
for set in dir1 dir2 dir3 dir4
do
[ -f "$set/"*"$datestr"* ] || all_exist=""
done
[ "$all_exist" ] && some_command

Answer 2

So this can really be divided into two tasks:
Find dates for which a set exists
Launch a command on each set
You are not revealing how your files are organized, but if you have something like boom20140112/a.txt and boom20140112/b.txt forming one set, and foo20140111/a.txt and foo20140111/c.txt another, you can find the dates with
dates () {
printf "%s\n" *201[0-9][0-9][0-9][0-9][0-9]/. |
sed -e 's%^[0-9]*%%' -e 's%/\.$%%' |
sort -u
}
If your sets look different, you can probably adapt this. The general idea is to obtain a list of pertinent file names, strip out the parts which aren't the date, and remove any duplicates. Now you have a list of dates.
Here is another implementation which assumes that you have files named tags/tags_(date)_a.txt and tags/tags_(date)_b.txt and input/samples_(date).txt forming one set per date, where date is formatted like 2014-01-12.
dates () {
printf "%s\n" input/* tags/* |
sed 's/.*_\(201[1-9]-[0-9][0-9]-[0-9][0-9]\)[_.].*/\1/' |
sort -u
}
Given that, loop over the dates and run your command on each set.
dates | while read -r date; do
command *$date/*
done