ex

#!/usr/bin/env sh
# vim: ft=sh ts=4 sw=4 sts=4 et :
# Extract files from archive, wisely

# Check if a file/directory does not exist
checkne() {
    if [ -e "$1" ]; then
        echo "Error: '$1' already exists"
        return 1
    fi
    return 0
}

print_help() {
    # No local in POSIX sh
    scriptname=$(basename "$0")
    cat <<EOF
$scriptname - archive extractor
Usage: $scriptname <file>

Supported formats:
  *.tar.Z    - compressed tar archive
  *.Z        - compressed file
  *.tar.bz2  - bzip2 tar archive
  *.tbz2     - bzip2 tar archive
  *.bz2      - bzip2 file
  *.tar.gz   - gzip tar archive
  *.tgz      - gzip tar archive
  *.gz       - gzip file
  *.tar.xz   - xz tar archive
  *.txz      - xz tar archive
  *.xz       - xz file
  *.tar.lzma - lzma tar archive
  *.lzma     - lzma file
  *.tar.zst  - zstd tar archive
  *.tzst     - zstd tar archive
  *.zst      - zstd file
  *.tar.lz4  - lz4 tar archive
  *.lz4      - lz4 file
  *.rar      - rar archive
  *.tar      - tar archive
  *.zip      - zip archive
  *.7z       - 7-zip archive
EOF
}

main() {
    if [ -z "$1" ] || [ "$1" = "-h" ] || [ "$1" = "--help" ]; then
        print_help
        return 0
    fi

    if [ ! -f "$1" ]; then
        echo "'$1' is not a valid file"
        return 1
    fi

    # No local in POSIX sh
    fname=$(basename "$1")

    # Extract directly if the archive contains only one file/directory,
    # else we extract it into a separate directory
    case "$1" in
    *.tar.Z)
        froot="${fname%.tar.Z}"
        if [ "$(tar tZf "$1" | wc -l)" -gt 1 ]; then
            checkne "$froot" && mkdir "$froot" &&
                tar xZf "$1" -C "$froot" || return 1
        else
            tar xZf "$1"
        fi
        ;;
    *.Z) uncompress "$1" ;;
    *.tar.bz2 | *.tbz2)
        froot="${fname%.*}"
        if [ "$(tar tjf "$1" | wc -l)" -gt 1 ]; then
            checkne "$froot" && mkdir "$froot" &&
                tar xjf "$1" -C "$froot" || return 1
        else
            tar xjf "$1"
        fi
        ;;
    *.bz2) bunzip2 "$1" ;;
    *.tar.gz | *.tgz)
        case "$fname" in
        *.tar.gz) froot="${fname%.tar.gz}" ;;
        *) froot="${fname%.tgz}" ;;
        esac
        if [ "$(tar tzf "$1" | wc -l)" -gt 1 ]; then
            checkne "$froot" && mkdir "$froot" &&
                tar xzf "$1" -C "$froot" || return 1
        else
            tar xzf "$1"
        fi
        ;;
    *.gz)
        froot="${fname%.gz}"
        checkne "$froot" && gunzip -c "$1" >"$froot" || return 1
        ;;
    *.tar.xz | *.txz)
        case "$fname" in
        *.tar.xz) froot="${fname%.tar.xz}" ;;
        *) froot="${fname%.txz}" ;;
        esac
        if [ "$(tar tJf "$1" | wc -l)" -gt 1 ]; then
            checkne "$froot" && mkdir "$froot" &&
                tar xJf "$1" -C "$froot" || return 1
        else
            tar xJf "$1"
        fi
        ;;
    *.xz) unxz "$1" ;;
    *.tar.lzma)
        froot="${fname%.tar.lzma}"
        if [ "$(tar --lzma -tf "$1" | wc -l)" -gt 1 ]; then
            checkne "$froot" && mkdir "$froot" &&
                tar --lzma -xf "$1" -C "$froot" || return 1
        else
            tar --lzma -xf "$1"
        fi
        ;;
    *.lzma) unlzma "$1" ;;
    *.tar.zst | *.tzst)
        case "$fname" in
        *.tar.zst) froot="${fname%.tar.zst}" ;;
        *) froot="${fname%.tzst}" ;;
        esac
        if [ "$(tar --zstd -tf "$1" | wc -l)" -gt 1 ]; then
            checkne "$froot" && mkdir "$froot" &&
                tar --zstd -xf "$1" -C "$froot" || return 1
        else
            tar --zstd -xf "$1"
        fi
        ;;
    *.zst) zstd -d "$1" ;;
    *.tar.lz4)
        froot="${fname%.tar.lz4}"
        if [ "$(tar --use-compress-program=lz4 -tf "$1" | wc -l)" -gt 1 ]; then
            checkne "$froot" && mkdir "$froot" &&
                tar --use-compress-program=lz4 -xf "$1" -C "$froot" || return 1
        else
            tar --use-compress-program=lz4 -xf "$1"
        fi
        ;;
    *.lz4) lz4 -d "$1" ;;
    *.rar)
        froot="${fname%.rar}"
        if unrar l "$1" | grep -q '^.*/$'; then
            checkne "$froot" && mkdir "$froot" &&
                unrar x "$1" "$froot" || return 1
        else
            unrar x "$1"
        fi
        ;;
    *.tar)
        froot="${fname%.tar}"
        if [ "$(tar tf "$1" | wc -l)" -gt 1 ]; then
            checkne "$froot" && mkdir "$froot" &&
                tar xf "$1" -C "$froot" || return 1
        else
            tar xf "$1"
        fi
        ;;
    *.zip)
        froot="${fname%.zip}"
        if zipinfo -1 "$1" | grep -q '^.*/$'; then
            checkne "$froot" && mkdir "$froot" &&
                unzip "$1" -d "$froot" || return 1
        else
            unzip "$1"
        fi
        ;;
    *.7z)
        froot="${fname%.7z}"
        if 7z l "$1" | grep -q '^.*/$'; then
            checkne "$froot" && mkdir "$froot" &&
                7z x "$1" -o"$froot" || return 1
        else
            7z x "$1"
        fi
        ;;
    *)
        echo "'$1' cannot be extracted"
        ;;
    esac
}

main "$1"