Linux中暂时没发现现成的命令，因此可用用shell脚本结合df -h命令来实现
实现思路：
1、输入一个路径
2、获得df -h信息
3、保存根目录的可用空间大小
4、除了跟根目录之外的其他挂载目录匹配路径，如果匹配成功，取该路径的可用空间，或者取根目录的可用空间
shell脚本：
#!/bin/bash
#########################################
#author:
# yxj
# BLOG:
# http://blog.csdn.net/u010317005
#usage:
# ./get_dir_avail_space [dir]
#e.g:
# ./get_dir_avail_space /root
# ./get_dir_avail_space
#########################################
############get test path###############
if [ -z $1 ];then
read -p "input the path(e.g: /root):" path
else
path=$1
fi
if [ "${path:0:1}" = "/" ];then
if [ ! -d ${path} ];then
# echo "create new path:${path}"
mkdir -p ${path}
fi
# echo "absolute directory:${path}"
else
pwd=`pwd`
if [ ! -d "${pwd}/${path}" ];then
# echo "create new path:${pwd}/${path}"
mkdir -p ${pwd}/${path}
fi
path=${pwd}/${path}
# echo "path:${path}"
fi
##########get data from df -h#############
df -h | while read line
do
#for var in $line
line_path=`echo ${line} | awk -F' ' '{print $6}'`
line_avail=`echo ${line} | awk -F' ' '{print $4}'`
if [ "${line_path:0:1}" != "/" ]; then
continue
fi
if [ "${line_path}" = "/" ]; then
root_avail=${line_avail}
#echo "root_avail:${root_avail}"
if [ -f /tmp/tmp_root_avail ];then
rm /tmp/tmp_root_avail
fi
echo ${root_avail} > /tmp/tmp_root_avail
continue
fi
path_length=${#line_path}
if [ "${path:0:${path_length}}" = "${line_path}" ];then
# echo "${path} contain path:${line_path}"
path_avail=${line_avail}
if [ -f /tmp/tmp_path_avail ];then
rm /tmp/tmp_path_avail
fi
echo ${path_avail} > /tmp/tmp_path_avail
break
fi
done
#############get data from temp file###############
if [ -f /tmp/tmp_path_avail ];then
path_avail=`cat /tmp/tmp_path_avail`
rm /tmp/tmp_path_avail
fi
if [ -f /tmp/tmp_root_avail ];then
root_avail=`cat /tmp/tmp_root_avail`
rm /tmp/tmp_root_avail
fi
###################compute######################
if [ -z ${path_avail} ];then
# echo "root_avail:${root_avail}"
# echo "path_avail=${path_avail}"
path_avail=${root_avail}
fi
echo "${path_avail}"
保存为get_dir_avail_path.sh
chmod 777 get_dir_avail_path.sh修改权限
#usage:
# ./get_dir_avail_space [dir]
#e.g:
# ./get_dir_avail_space /root
# ./get_dir_avail_space