Batch processing two sets of files

Question

Assume that I have two sets of files foo_A_uid.bar and foo_B_uid.bar. Each set contains (a known) number of files. Now, I want to process corresponding pairs using some tool (ImageMagick in my case), that is I want to run some_command foo_A_i.bar foo_B_i.bar out_i.bar, where out_i.bar is the result/output when running the tool on the pair foo_A_i.bar and foo_B_i.bar for some fixed i.

My question is how can I batch this process? Some python, bash script?

Clarification: By set of files I mean a list of files, all start with the same initial, then some UID and having the same extension. This hold for both input sets and the output.

Answer 1

Here's a possible solution, which works, although I don't know if it's a good one.

#!/bin/bash

EXPECTED_ARGS=3
E_BADARGS=65

if [ $# -ne $EXPECTED_ARGS ]
then
    echo Not the right number of arguments
    exit $E_BADARGS
fi

for i in $( ls $1* ); do
    TMP=$(echo $2$(echo $i | cut -d'_' -f2))
    TMP2=$(echo $3$(echo $i | cut -d'_' -f2))
    convert $i $TMP +append $TMP2
done

Running it should be something like:

script foo_A_ foo_B_ out_

Answer 2

#!/bin/bash
count=$(wc -l foo_A_uid.bar)
for line in $(seq 1 ${count/ */})
do
    aline=$(sed -n $line"p" foo_A_uid.bar)
    bline=$(sed -n $line"p" foo_A_uid.bar)
    yourcommand "$aline" "$bline"
done

Assuming both files are sorted, the count-line get's the number of lines in file a. Then a loop runs over all values from 1..count. The count-variable contains the name of the file, which is cut off with ${count/ */}. With sed, you get the same line from both files. -n means 'no printing by default', $line"p" will then just print line $line.