1.Shell判断文件是否存在
#!/bin/sh myPath="/var/log/httpd/" myFile="/var /log/httpd/access.log" # 这里的-x 参数判断$myPath是否存在并且是否具有可执行权限 if [ ! -x "$myPath" ]; then mkdir "$myPath" fi # 这里的-d 参数判断$myPath是否存在 if [ ! -d "$myPath" ]; then mkdir "$myPath" fi # 这里的-f参数判断$myFile是否存在 if [ ! -f "$myFile" ]; then touch "$myFile" fi # 其他参数还有-n,-n是判断一个变量是否是否有值 if [ ! -n "$myVar" ]; then echo "$myVar is empty" exit 0 fi # 两个变量判断是否相等 if [ "$var1" = "$var2" ]; then echo '$var1 eq $var2' else echo '$var1 not eq $var2' fi -f 和-e的区别 Conditional Logic on Files -a file exists. -b file exists and is a block special file. -c file exists and is a character special file. -d file exists and is a directory. -e file exists (just the same as -a). -f file exists and is a regular file. -g file exists and has its setgid(2) bit set. -G file exists and has the same group ID as this process. -k file exists and has its sticky bit set. -L file exists and is a symbolic link. -n string length is not zero. -o Named option is set on. -O file exists and is owned by the user ID of this process. -p file exists and is a first in, first out (FIFO) special file or named pipe. -r file exists and is readable by the current process. -s file exists and has a size greater than zero. -S file exists and is a socket. -t file descriptor number fildes is open and associated with a terminal device. -u file exists and has its setuid(2) bit set. -w file exists and is writable by the current process. -x file exists and is executable by the current process. -z string length is zero. 是用 -s 还是用 -f 这个区别是很大的！
2.Shell算术运算
$[1+2] #value:3
`expr 1 + 2` #value:3
$((1 + 2)) #value:3
3.遍历文件的每行数据
while read lines
do
echo $lines
done<filename#filename为文件名
4.提取行数据
awk语法：awk /pattern/{action} filename
awk简单用法
获取文件第一，列的数据:
awk '{print $1}' filename
5.显示日期格式为yyyyMMdd
date +%Y%m%d
6.Map通过key值排序的简单小例子
HashMap<String, String> map = new HashMap<String, String>();
map.put("2012-07-04", "2012-07-04");
map.put("2012-07-03", "2012-07-03");
map.put("2012-07-07", "2012-07-07");
map.put("2012-07-01", "2012-07-01");
Object[] key = map.keySet().toArray();
Arrays.sort(key);
for (int i = 0; i < key.length; i++) {
System.out.println(map.get(key[i]));
}