Linux: remove file extensions for multiple files

Question

I have many files with .txt extension. How to remove .txt extension for multiple files in linux?

I found that

rename .old .new *.old

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Answer 1

In case it helps, here's how I do it with zsh:

for f in ./**/*.old; do
    mv "${f}" "${f%.old}"
done

The ${x%pattern} construct in zsh removes the shortest occurence of pattern at the end of $x. Here it is abstracted as a function:

function chgext () {
    local srcext=".old"
    local dstext=""
    local dir="."

    [[ "$#" -ge 1 ]] && srcext="$1"
    [[ "$#" -gt 2 ]] && dstext="$2" dir="$3" || dir="${2:-.}"

    local bname=''
    for f in "${dir}"/**/*"${srcext}"; do
        bname="${f%${srcext}}"
        echo "${bname}{${srcext} → ${dstext}}"
        mv "${f}" "${bname}${dstext}"
    done
}

Usage:

chgext
chgext src
chgext src dir
chgext src dst dir

Where `src` is the extension to find (default: ".old")
      `dst` is the extension to replace with (default: "")
      `dir` is the directory to act on (default: ".")