xargs with multiple arguments

I have a source input, input.txt

a.txt
b.txt
c.txt

I want to feed these input into a program as the following:

my-program --file=a.txt --file=b.txt --file=c.txt

So I try to use xargs, but with no luck.

cat input.txt | xargs -i echo "my-program --file"{}

It gives

my-program --file=a.txt
my-program --file=b.txt
my-program --file=c.txt

But I want

my-program --file=a.txt --file=b.txt --file=c.txt

Any idea?

Solution 1:

Don't listen to all of them. :) Just look at this example:

echo argument1 argument2 argument3 | xargs -l bash -c 'echo this is first:$0 second:$1 third:$2'

Output will be:

this is first:argument1 second:argument2 third:argument3

Solution 2:

None of the solutions given so far deals correctly with file names containing space. Some even fail if the file names contain ' or ". If your input files are generated by users, you should be prepared for surprising file names.

GNU Parallel deals nicely with these file names and gives you (at least) 3 different solutions. If your program takes 3 and only 3 arguments then this will work:

(echo a1.txt; echo b1.txt; echo c1.txt;
 echo a2.txt; echo b2.txt; echo c2.txt;) |
parallel -N 3 my-program --file={1} --file={2} --file={3}

Or:

(echo a1.txt; echo b1.txt; echo c1.txt;
 echo a2.txt; echo b2.txt; echo c2.txt;) |
parallel -X -N 3 my-program --file={}

If, however, your program takes as many arguments as will fit on the command line:

(echo a1.txt; echo b1.txt; echo c1.txt;
 echo d1.txt; echo e1.txt; echo f1.txt;) |
parallel -X my-program --file={}

Watch the intro video to learn more: http://www.youtube.com/watch?v=OpaiGYxkSuQ

Solution 3:

How about:

echo $'a.txt\nb.txt\nc.txt' | xargs -n 3 sh -c '
   echo my-program --file="$1" --file="$2" --file="$3"
' argv0

Solution 4:

It's simpler if you use two xargs invocations: 1st to transform each line into --file=..., 2nd to actually do the xargs thing ->

$ cat input.txt | xargs -I@ echo --file=@ | xargs echo my-program
my-program --file=a.txt --file=b.txt --file=c.txt