fcat, cat for llms

fcat.sh

#!/usr/bin/env bash

# detect type based on extension
get_type() {
    local file="$1"
    case "$file" in
        *.py) echo "python" ;;
        *.sh) echo "shell" ;;
        *.c)  echo "c" ;;
        *.cpp|*.cc|*.cxx) echo "cpp" ;;
        *.js) echo "javascript" ;;
        *.jsx) echo "jsx" ;;
        *.ts) echo "typescript" ;;
        *.tsx) echo "tsx" ;;
        *.java) echo "java" ;;
        *.go) echo "go" ;;
        *.rb) echo "ruby" ;;
        *.php) echo "php" ;;
        *.html|*.htm) echo "html" ;;
        *.css) echo "css" ;;
        *.json) echo "json" ;;
        *.yaml|*.yml) echo "yaml" ;;
        *.md) echo "markdown" ;;
        *) detect_from_shebang "$file" ;;
    esac
}

# detect from shebang if no extension matched
detect_from_shebang() {
    local file="$1"
    if [ -f "$file" ]; then
        local firstline
        firstline=$(head -n 1 "$file")
        case "$firstline" in
            *python*) echo "python" ;;
            *bash*|*sh) echo "shell" ;;
            *node*|*deno*) echo "javascript" ;;
            *ruby*) echo "ruby" ;;
            *php*) echo "php" ;;
            *perl*) echo "perl" ;;
            *go*) echo "go" ;;
            *) echo "text" ;;
        esac
    else
        echo "text"
    fi
}

# choose comment style
get_comment_prefix() {
    local type="$1"
    case "$type" in
        python|shell|ruby|perl) echo "#" ;;
        *) echo "//" ;;
    esac
}

# collect files from args or stdin
files=()
if [ "$#" -gt 0 ]; then
    files=("$@")
else
    while IFS= read -r line; do
        [ -n "$line" ] && files+=("$line")
    done
fi

for f in "${files[@]}"; do
    [ -d "$f" ] && { continue; }
    [ -f "$f" ] || { echo "Skipping missing file: $f" >&2; continue; }
    [ "$f" != "${files[0]}" ] && echo
    type=$(get_type "$f")
    prefix=$(get_comment_prefix "$type")

    echo "\`\`\`$type"
    echo "$prefix path: $f"
    cat "$f"
    echo "\`\`\`" # blank line separator
done

fcat.sh

fcat prints files wrapped in Markdown code fences, with automatic language detection.

I made this to easily put whole files (with their path) into LLMs.

Install

cp fcat ~/.local/bin/fcat
chmod +x ~/.local/bin/fcat

Make sure ~/.local/bin is in your PATH.

Use

# Single file
$ fcat file.py

# All files in directory 
$ find . -type f | fcat

# To clipboard (WSL)
$ fcat *.yml | clip.exe

# To clipboard (linux)
$ fcat *.yml | xclip -selection clipboard