[SOLVED] Convert first letter to lowercase using sed

Issue

I am running a Docker Alpine based image which has bash installed.

bash --version
GNU bash, version 4.3.48(1)-release (x86_64-alpine-linux-musl)

In the following command, i am trying to convert first letter of month to lowercase but it's not working:

find ../ -type f -name "*.md" \
        -exec bash -c '
            f=${1#./}
            gzip -9 "$f"
            mv "$f".gz "$f"
            aws s3 cp "$f" s3://bucket_name/ --metadata time=$(date +%d-%b-%Y.%H%M | sed '\''s#\([A-Z]\)#\L\1#'\'') ' _ {} \;

The date attribute it assigns to the file(s) is:

"Metadata": {
    "timestamp": "10-LSep-2018.1054"
}

\L is not working in this case. The expected date should have been "10-sep-2018.1054"

How can i get it working with the bash version present in Docker image?

Solution

As it turns out OP only has access to a minimal version of sed that does not recognize the \L replacement command and for his use case de-capitalizing ALL letters in the output is acceptable.

The most straightforward way to achieve this is with the command

tr [:upper:] [:lower:]

Answered By - Sam

Answer Checked By - Robin (WPSolving Admin)