Rename tsv file columns with shorter names

reheader.sh

#!/bin/bash

# Create a temporary directory for storing intermediate files
TMPDIR=${TMP:-/tmp}
HEADER_FILE="$TMPDIR/header_$(date +%s%N).txt"
NEW_HEAD_FILE="$TMPDIR/renamed0_$(date +%s%N).txt"
RANDOM_FILE="$TMPDIR/renamed_$(date +%s%N).txt"
INPUT_REST_FILE="$TMPDIR/input_rest_$(date +%s%N).txt"

# Function to process input
process_input() {
    local input="$1"
    # Extract the header line
    local header
    if [[ -n "$input" ]]; then
        header=$(head -n 1 "$input")
        tail -n +2 "$input" > "$INPUT_REST_FILE"
    else
        read -r header
        cat > "$INPUT_REST_FILE"
    fi

    # Save header to a random temporary file
    echo -e "$header" > "$HEADER_FILE"

    # Use llm to generate new column names
    cat "$HEADER_FILE" | llm -m gemini-1.5-flash-latest -s \
        "these are column names. Make them shorter by removing unnecessary text. Only report the new column names. report one new column name per line" > "$NEW_HEAD_FILE"

    # Read the new column names
    if [[ ! -s "$NEW_HEAD_FILE" ]]; then
        echo "Error: No new column names generated." >&2
        exit 1
    fi

    local new_header
    # Remove commas, trim spaces, and ensure the header is tab-delimited
    new_header=$(tr ',' '\t' < "$NEW_HEAD_FILE" | sed 's/^ //;s/ \t/\t/g' | tr '\n' '\t' | sed 's/\t$//')

    # Print the new header
    echo -e "$new_header"

    # Print the rest of the file or input
    cat "$INPUT_REST_FILE"

    # Clean up
    rm -f "$HEADER_FILE" "$INPUT_REST_FILE" "$RANDOM_FILE"
}

# Main logic to handle piped input or file
if [[ -t 0 ]]; then
    # No piped input; check for file argument
    if [[ -n "$1" && -f "$1" ]]; then
        process_input "$1"
    else
        echo "Usage: $0 <file> or pipe input to the script" >&2
        exit 1
    fi
else
    # Handle piped input
    process_input
fi