增加了一个输出目录树结构的脚本tree.sh，输模拟linux中的tree命令，可在BSD、Linux中运行，用于弥补那些没有tree命令的系统。

#!/bin/sh
#
# tree.sh
# A tool that display the dictionary structure in dos's
# tree command style.
# By Matthew <matthew@linuxforum.net>
#
#    __@
#  _ \<_
# (_)/(_) 
# Apr 29 2003
#
# Tested on slackware, openbsd, netbsd, freebsd.
#
# Just for fun.
#

# The name of the ls program, please use
# the absolute path, otherwise, there
# may be get some strange errors.
#
LSPROG="/bin/ls"

# COLOR DEFINE
# ============
#
DIR="\033[01;34m"
EXE="\033[01;32m"
DEV="\033[01;33m"
LNK="\033[01;36m"
ZIP="\033[01;31m"
SOCK="\033[01;35m"
NULL="\033[00m"

TRUE=0
FALSE=1
LAYERS=0
FILECOUNT=0
DIRCOUNT=0

COLOR=${TRUE}
if [ "${1#-n}" != "${1}" ]; then
    shift
    COLOR=${FALSE}
fi

ROOT=${1:-.}

if [ ${COLOR} -eq ${FALSE} ]; then
    DIR=""
    EXE=""
    DEV=""
    LNK=""
    ZIP=""
    SOCK=""
    NULL=""
fi

# print_dash
# ==========
# Print the structure lines
#
print_dash()
{
    local i=0
    local num=$1
    
    while [ $i -lt $num ]; do
        echo -n "|   "

        i=`expr $i + 1`
    done

    echo -n "|-- "
}

# ispkg
# =====
# Test if the file is a package like:
# .gz .tar .tgz .tar.gz .zip .rar .rpm
# and etc.
#
ispkg()
{
    local f=$1
    local i    

    # Package extension list, you can add your coustom
    # extensions in it.
    #
    local pkg__ext=".gz .tar .tgz .tar.gz .zip .rar .rpm"

    # if the file's suffix contain any package extension
    # then cut it.

    for i in $pkg__ext; do
        f=${f%$i}
    done

    if [ "$f" != "$1" ]; then
        return $TRUE
    else
        return $FALSE
    fi
}

# mktree
# ======
# The main function, that print the 
# dictionary structure in dos's tree
# command style. It's runs in nesting.
#
mktree()
{
    local f
    local OLDIFS=$IFS

    IFS='
    '
    for f in `$LSPROG -1 $1`; do
        f=${f%/}
        f=${f##*/}
    
        # If dictionary then print it and enter
        # the nesting block.
        if [ -d $1/$f ]; then
            print_dash $LAYERS
            echo -e "${DIR}$f${NULL}"
            DIRCOUNT=`expr $DIRCOUNT + 1`

            LAYERS=`expr $LAYERS + 1`
            mktree $1/$f
        else
            print_dash $LAYERS
            # file is a symbol link
            if [ -L $1/$f ]; then 
                echo -e "${LNK}$f${NULL}"
            # file is executable
            elif [ -x $1/$f ]; then
                echo -e "${EXE}$f${NULL}"
            # file is a device
            elif [ -c $1/$f -o -b $1/$f ]; then
                echo -e "${DEV}$f${NULL}"
            # file is a socket
            elif [ -S $1/$f ]; then
                echo -e "${SOCK}$f${NULL}"
            # file is a package
            elif `ispkg $f`; then
                echo -e "${ZIP}$f${NULL}" 
            else    
                echo -e "$f"
            fi
            
            FILECOUNT=`expr $FILECOUNT + 1`
        fi
    done

    LAYERS=`expr $LAYERS - 1`

    export IFS=$OLDIFS
}

echo $ROOT
mktree $ROOT
echo "\`"
echo "$DIRCOUNT directories, $FILECOUNT files"