#String Comparison Operators
Operator True if...
str1 = str2a str1 matches str2
str1 != str2 str1 does not match str2
str1 < str2 str1 is less than str2
str1 > str2 str1 is greater than str2
-n str1 str1 is not null (has length greater than 0)
-z str1 str1 is null (has length 0)
#File Attribute Operators
Operator True if...
-d file file exists and is a directory
-e file file exists
-f file file exists and is a regular file (i.e., not a directory or other special type of file)
-r file You have read permission on file
-s file file exists and is not empty
-w file You have write permission on file
-x file You have execute permission on file, or directory search permission if it is a directory
-O file You own file
-G file file's group ID matches yours (or one of yours, if you are in multiple groups).
file1 -nt file2 file1 is newer than file2
file1 -ot file2 file1 is older than file2
#Arithmetic Test Operators
Test Comparison
-lt Less than
-le Less than or equal
-eq Equal
-ge Greater than or equal
-gt Greater than
-ne Not equal
判断某文件的修改时间：
stat 文件 | grep Modify | awk '{print $2}'
查看时间：
date +%F = date +%Y-%m-%d
date +'%F %T' = date +'%Y-%m-%d %H:%M:%S'
根据进程名字找到pid：
ps -ef | grep 'HRegionServer' | grep -v 'grep' | awk '{print $2}'
远程根据进程名杀死进程
pid=`ssh server3 ps -ef | grep 'HRegionServer' | grep -v 'grep' | awk '{print $2}'`
ssh server3 kill -9 $pid
改ip
sudo ifconfig eth0:0 192.168.244.128 broadcast 192.168.244.255 netmask 255.255.255.0 up