如何用 Shell 脚本编写递归程序

UNIX Shell 脚本类似 DOS 的批处理命令，但比较起来 UNIX Shell 的功能更强大，在某些方面，Shell 甚至超过了一些高级语言。

下边的 Shell 脚本演示了如何用 Shell 脚本编写递归程序。

运行前先执行下述准备命令：

??ln tree.sh /usr/bin/tree

??ln tree.sh /usr/bin/wtree

??ln tree.sh /usr/bin/dtree

??rm tree.sh

# tree.sh

# Depth first Directory list

dtree() {

PWD=`pwd|sed 's/\/\$//`

for d in $*

do

echo "${PWD}/$d"

[ -d "$d" -a -x "$d" ] && {

cd "$d"

dtree *

cd ..

PWD=`pwd|sed 's/\/\$//` # restore PWD

}

done

}

# Depth first Directory list

wtree() {

PWD=`pwd|sed 's/\/\$//`

for d in $*

do

echo ${PWD}/$d

done

for d in $*

do

[ -d "$d" -a -x "$d" ] && {

cd $d

wtree *

cd ..

}

done

}

# Directory list

tree() {

PWD=`pwd|sed 's/\/\$//`

for d in $*

do

echo ${PWD}/$d

done

}

# main

TREE=`basename $0`

if [ "$1" ]

then DIR="$1"

else DIR="."

fi

if cd $DIR

then $TREE *

else echo "$0: Directory $1 read fail."

fi

# (End)