Create new file but add number if filename already exists in bash

Question

I found similar questions but not in Linux/Bash

I want my script to create a file with a given name (via user input) but add number at the end if filename already ex

Answer 1

The following script can help you. You should not be running several copies of the script at the same time to avoid race condition.

name=somefile
if [[ -e $name.ext || -L $name.ext ]] ; then
    i=0
    while [[ -e $name-$i.ext || -L $name-$i.ext ]] ; do
        let i++
    done
    name=$name-$i
fi
touch -- "$name".ext

Answer 2

A simple repackaging of choroba's answer as a generalized function:

autoincr() {
    f="$1"
    ext=""

    # Extract the file extension (if any), with preceeding '.'
    [[ "$f" == *.* ]] && ext=".${f##*.}"

    if [[ -e "$f" ]] ; then
        i=1
        f="${f%.*}";

        while [[ -e "${f}_${i}${ext}" ]]; do
            let i++
        done

        f="${f}_${i}${ext}"
    fi
    echo "$f"
}

touch "$(autoincr "somefile.ext")"