Generate unique filename for fswebcam

Question

I have fswebcam installed in my ubuntu. I want the fswebcam to provide output as img1, img2 (if img1 is there), img3, img4... etc

I tried:

sudo fswebcam img

It stores the files as img but replaces the existing one instead of storing as img2.
Is there any specific type of unix command to store the filename as I specified?

Answer 1

Or you could just use its built in strftime capability to generate each file with the current time in the filename

--save pic%Y-%m-%d_%H:%M:%S.jpg

Answer 2

I would also like to know that specific command if it exists. Meanwhile, I also needed to do that, and I used a workaround as follows (adapted to your needs):

f() {
    PREFIX="./img"
    FILES=$(ls $PREFIX* 2> /dev/null)
    LAST=$(sort -n <<<"${FILES//$PREFIX}" | tail -n1)
    echo $PREFIX$((LAST+1))
}

FILES contains al the filenames separated by \n.
LAST will have nothing, or the max number after the $PREFIX.
Finally, the function echo'es the last filename incremented by 1.

So, once you have defined f (or a more significant name), you can call your command like this:

sudo fswebcam $(f)

---

Example

$ ls
img1  img10  img11  img2  img3  img4  img5  img6  img7  img8  img9
$ echo $(f) # here I'm using "echo" instead of "sudo fswebcam"
./img12

---

f step by step

$ FILES=$(ls $PREFIX* 2> /dev/null)
$ cat <<<"$FILES"
./img1
./img10
./img11
./img2
./img3
./img4
./img5
./img6
./img7
./img8
./img9
$ LAST=$(sort -n <<<"${FILES//$PREFIX}" | tail -n1)
$ echo $LAST
11
$ echo $PREFIX$((LAST+1))
./img12