untar: A simple shell script to untar a tarball.

untar

#!/bin/bash

# 
# A simple command to untar any tarball.
# 
# For times when you don't care whether it was compressed
# with bzip2 or gzip, you just want to untar it already!
# 
# Usage: untar [-v|--verbose] file
# 
# Author: John Croisant
# 
# License: Do whatever you want.
# 
# History:
# 2009-10-05: Initial version. (JC)
# 2009-10-06: Added -v/--verbose flag. (JC)
#             Improved file type detection, w/ support for symlinks. (JC)
# 2011-05-13: Added -l/-t/--list and -x/--extract flags. (JC)
#             Added detection for .tar.xz files.
# 

script=$(basename $0)


opts=`getopt -n "$script" -o "vltx" -l "verbose" -l "list" -l "extract" -- "$@"`
if [ ! $? -eq 0 ]; then exit 1; fi # getopt failed
# Overwrite the script's positional parameters with getopt's output:
set -- $opts


verbose=false
action=extract

while [ $# -gt 0 ]; do
    case "$1" in
        -v | --verbose)
            verbose=true;;
        -l | -t | --list)
            action=list;;
        -x | --extract)
            action=extract;;
        --)
            shift; break;;
        *)
            break;
    esac
    shift
done


function file_type {
    if [ ! -e $1 ]; then
        echo "missing"; return 1;
    fi

    case $(file --brief --dereference --mime --uncompress $1) in
        application/x-tar*application/x-gzip*)
            echo "tar.gz";;
        application/x-tar*application/x-bzip2*)
            echo "tar.bz2";;
        application/x-tar*application/x-xz*)
            echo "tar.xz";;
        application/x-tar*)
            echo "tar";;
        *)
            echo "unknown"; return 1;;
    esac
}


function handle_file {
    target=`eval echo $1`  # strip 'quotes' that getopt made

    tarflags=

    if [ true = $verbose ]; then
        tarflags="-v $flags"
    fi

    case $action in
        extract)
            tarflags="$tarflags -x";;
        list)
            tarflags="$tarflags -t";;
    esac

    case $(file_type $target) in
        *) ;;
        missing)
            echo "$script: $target: No such file"
            return 1;;
        tar.gz)
            tarflags="$tarflags -z";;
        tar.bz2)
            tarflags="$tarflags -j";;
        tar.xz)
            tarflags="$tarflags -J";;
        tar)
            ;;
        *)
            echo "$script: $target: That's not a tarball, silly"
            return 1;;
    esac

    tar $tarflags -f $target;
}


handle_file $1